recovered, the percentage rising as the depth increases. Thus the diver
Alexander Lambert, who performed some plucky feats during the driving
of the Severn Tunnel,[18] received £4,000 for the recovery of £70,000
worth of gold from the _Alphonso XII._, sunk off Grand Canary. Divers
Ridyard and Penk recovered £50,000 from the _Hamilla Mitchell_, which
lay in 160 feet of water off Shanghai, after nearly being captured
by Chinese pirates; and we could add many other instances in which
treasure has been rescued from the maw of the sea.

The most useful sphere for a diver is undoubtedly connected with
the harbour work and the cleaning of ships' bottoms. For the latter
purpose every large warship in the British Navy carries at least one
diver. After ships have been long in the water barnacles and marine
growths accumulate on the below-water plates in such quantities as
to seriously diminish the ship's speed, which means a great waste of
fuel, and would entail a loss of efficiency in case of war breaking
out. Armed with the proper tools, a gang of divers will soon clean the
"foul bottom," at a much smaller cost of time and money than would be
incurred by dry-docking the vessel.

The Navy has at Portsmouth, Sheerness, and Devonport schools where
diving is taught to picked men, the depth in which they work being
gradually increased to 120 feet. Messrs. Siebe and Gorman employ
hundreds of divers in all parts of the world, on all kinds of submarine
work, and they are able to boast that never has a defect in their
apparatus been responsible for a single death. This is due both to the
very careful tests to which every article is subjected before it leaves
their works, and also to the thorough training given to their employés.

In the sponge and pearl-fishing industries the diving dress is
gradually ousting the unaided powers of the naked diver. One man
equipped with a standard dress can do the work of twenty natural
divers, and do it more efficiently, as he can pick and choose his
material.

This chapter may conclude with a reference to the apparatus now used
in exploring or rescue work in mines, where deadly fumes have overcome
the miners. It consists of an air-tight mask connected by tubes to a
chamber full of oxygen and to a bag containing materials which absorb
the carbonic acid of exhaled air. The wearer uses the same air over and
over again, and is able to remain independent of the outer atmosphere
for more than an hour. The apparatus is also useful for firemen when
they have to pass through thick smoke.

FOOTNOTE:

[18] Vide _The Romance of Modern Engineering_, p. 212.

CHAPTER XV

APPARATUS FOR RAISING SUNKEN SHIPS AND TREASURE

It is somewhat curious that, while the sciences connected with the
building of ships have progressed with giant strides, little attention
has been paid to the art of raising vessels which have found watery
graves in comparatively shallow depths. The total shipping losses of a
single year make terrible reading, since they represent the extinction
of many brave sailors and the disappearance of huge masses of the
world's wealth. A life lost is lost for ever, but cargoes can be
recovered if not sunk in water deeper than 180 feet. Yet with all our
modern machinery the percentage of vessels raised from even shallow
depths is small.

There are practically only two methods of raising a foundered ship:
first, to caulk up all leaks and pump her dry; and secondly, to pass
cables under her, and lift her bodily by the aid of pontoons, or
"camels."

The second method is that more generally used, especially in the
estuaries of big rivers where there is a considerable tide. The
pontoons, having a united displacement greater than that of the vessel
to be raised, are brought over her at low tide. Divers pass under her
bottom huge steel cables, which are attached to the "camels." As
the tide flows the pontoons sink until they have displaced a weight
of water equal to that of the vessel, and then they begin to raise
her, and can be towed into shallower water, to repeat the process if
necessary next tide. As soon as the deck is above water the vessel may
be pumped empty, when all leaks have been stopped.

In water where there is no tide the natural lift must be replaced
by artificial power. Under such circumstances the salvage firms use
lighters provided with powerful winches, each able to lift up to 800
tons on huge steel cables nearly a foot in diameter. The winches can
be moved across a lighter, the cables falling perpendicularly, through
transverse wells almost dividing the lighter into separate lengths, so
as to get a direct pull. If the wreck has only half the displacement of
the lighters, the cables can be passed over rollers on the inner edges
of the pontoons, the weight of the raising vessel being counteracted by
water let into compartments in the outer side of the pontoons.

There are ten great salvage companies in the British Isles and Europe.
The best equipped of these is the Neptune Company, of Stockholm, which
has raised 1,500 vessels, worth over £5,000,000 sterling even in their
damaged condition, among them the ill-fated submarine "A1." Yet this
total represents but a small part of the wealth that has gone to the
bottom within a short distance of our coasts.

Turning from the salvage of wrecks to the salvage of precious metal and
bulky objects that are known to strew the sea-floor in many places,
we must notice the Hydroscope, the invention of Cavaliere Pino, an
Italian.

In 1702 there sank in Vigo Bay, on the north-west coast of Spain,
twenty-five galleons laden with treasure from America, as the result
of an attack by English and Dutch men-of-war. Gold representing
£28,000,000 was on those vessels. Down it went to the bottom, and there
it is still.

So rich a prize has naturally not failed to attract daring spirits,
among whom was Giuseppe Pino. This inventor has produced many devices,
the most notable among them the hydroscope, which may best be described
as a huge telescope for peering into the depths of the sea. A large
circular tank floats on the top of the water. From the centre of its
bottom hangs a series of tubes fitting one into the other, so that the
whole series can be shortened or lengthened at will. Through the tubes
a man can descend to the chamber at their lower extremity, in the sides
of which are twelve lenses specially made by Saint Gobain, of Paris,
which act as submarine telescopes.

Pino's hydroscope has been at work for some time in Vigo Bay, its
operations closely watched by a Spanish war vessel, which will exact 20
per cent. of all treasure recovered. While the hydroscope acts as an
eye, the lifting of an object is accomplished by attaching to it large
canvas bags furnished with air-tight internal rubber bladders. These
have air pumped into them till its pressure overcomes that of the water
outside, and the bag then rises like a cork, carrying its load with it.
An "elevator"--nine sacks fixed to one frame--will raise twenty-five to
thirty tons.

So far Cavaliere Pino has salvaged old Spanish guns, cannon-balls, and
pieces of valuable old wood; and presently he may alight on the specie
which is the main object of his search.

Another Spanish wreck, the _Florida_, which was a unit of the Spanish
Armada, and sank in Tobermory Bay, the Isle of Mull, has many times
been attacked by divers. The last attempt made to recover the treasure
which that ill-fated vessel was reputed to bear is that of the
steam lighter _Sealight_, which employed a very powerful sand pump
to suck up any objects which it might encounter on the sea-bottom.
Many interesting relics have been raised by the pumps and attendant
divers--coins, bones, jewels, timbers, cannon, muskets, pistols,
swords, and a compass, which is so constructed that pressure on the top
causes the legs to spread. One of the cannon, fifty-four inches long,
has a separate powder chamber, the shot and wad still in the gun, and
traces of powder in the chamber. It is curious that what we usually
consider so modern an invention as the breech-loading cannon should
be found side by side with stone balls. The heavier objects were, of
course, raised by divers. In this quest also the treasure deposit has
not yet been tapped.

CHAPTER XVI

THE HANDLING OF GRAIN

THE ELEVATOR--THE SUCTION PNEUMATIC GRAIN-LIFTER--THE PNEUMATIC BLAST
GRAIN-LIFTER--THE COMBINED SYSTEM

THE ELEVATOR

On or near the quays of our large seaports, London, Liverpool,
Manchester, Bristol, Hull, Leith, Dublin, may be seen huge buildings of
severe and ugly outline, utterly devoid of any attempt at decoration.
Yet we should view them with respect, for they are to the inhabitants
of the British Isles what the inland granaries of Egypt were to the
dwellers by the Nile in the time of Joseph. Could we strip off the
roofs and walls of these structures, we should see vast bins full of
wheat, or spacious floors deeply strewn with the material for countless
loaves. The grain warehouses of Britain--the Americans would term them
"elevators"--have a total capacity of 10,000,000 quarters. Multiply
those figures by eight, and you have the number of bushels, each of
which will yield the flour for about forty 2-lb. loaves.

In these granaries is stored the grain which comes from abroad. With
the opening up of new lands in North and South America, and the
exploitation of the great wheat-growing steppes of Russia, English
agriculture has declined, and we are content to import five-sixths of
our breadstuffs, and an even larger proportion of grain foods for
domestic animals. It arrives from the United States, India, Russia,
Argentina, Canada, and Australia in vessels often built specially for
grain transport; and as it cannot be immediately distributed, must be
stored in bulk in properly designed buildings.

These contain either many storeys, over which the grain is spread to
get rid of superfluous moisture which might cause dangerous heating; or
huge bins, or "silos," in which it can be kept from contact with the
air. Experiments have proved that wheat is more successfully preserved
if the air is excluded than if left in the open, provided that it
is dry. The ancient Egyptians used brick granaries, filled from the
top, and tapped at the bottom, in which, to judge by the account of a
grievous famine given in the book of Genesis, their wheat was preserved
for at least seven years. During last century the silo fell into
disrepute; but now we have gone back to the Egyptian plan of closed
bins, which are constructed of wood, brick, ferro-concrete, or iron,
and are of square, hexagonal, or round section. They are set close
together, many under one roof, to economise space; as many as 2,985,000
bushels being provided for in the largest English storehouse.

Such vast quantities of grain require well-devised machinery for their
transport from ship to bin or floor, weighing, clearing, and for
their transference to barges, coasting vessels, or railway trucks.
The Alexander Grain Warehouse of Liverpool may be taken as a typical
example of a well-equipped silo granary. It measures 240 by 172 feet,
and contains 250 hexagonal bins of brickwork, each 80 feet deep and
12 feet in diameter. The grain is lifted from barges by four elevators
placed at intervals along the edge of the quay. The elevator is a
wooden case, 40 or 50 feet high, in which an endless band furnished
with buckets travels over two rollers placed at the top and bottom.
These are let down into the hold and scoop up the grain at the rate
of from 75 to 150 tons per hour, according to their size. As soon as
a bucket reaches the top roller it empties its charge into a spout,
which delivers the grain into a bin, whence it is lifted again 32
feet by a second elevator to a bin from which it flows by gravity to
a weighing hopper beneath; and as soon as two tons has collected, the
contents are emptied automatically into a distributing hopper. After
all this, the grain still has a long journey before it; for it is now
shot out on to an endless, flat conveyer belt moving at a rate of 9
to 10 feet per second. It is carried horizontally by this for some
distance along the quay, and falls on to a second belt moving at right
angles to the first, which whisks it off to the receiving elevators of
the storehouse. Once more it is lifted, this time 132 feet, to the top
floor of the building, and dropped on to a third belt, which runs over
a movable throwing-off carriage. This can be placed at any point of the
belt's travel, to transfer the grain to any of the spouts leading to
the 250 bins.

Here it rests for a time. When needed for the market it flows out at
the bottom of a bin on to belts leading to delivery elevators, from
which it may be either passed back to a storage bin after being well
aired, or shot into wagons or vessels. From first to last a single
grain may have to travel three miles between the ship and the truck
without being touched once by a human hand.

The vertical transport of grain is generally effected by an endless
belt, to which buckets are attached at short intervals. The grain,
fed to the buckets either by hand or by mechanical means, is scooped
up, whirled aloft, and when it has passed the topmost point of its
travel, and just as the bucket is commencing the descent, it flies by
centrifugal force into a hopper which guides it to the travelling belt,
as already described.

Of late years, however, much attention has been paid to pneumatic
methods of elevating, by which a cargo is transferred from ship to
storehouse, or from ship to ship, through flexible tubes, the motive
power being either the pressure of atmospheric air rushing in to fill
a vacuum, or high-pressure air which blows the grain through the tube
in much the same way as a steam injector forces water into a boiler.
Sometimes both systems are used in combination. We will first consider
these methods separately.

THE SUCTION PNEUMATIC GRAIN-LIFTER

is the invention of Mr. Fred E. Duckham, engineer of the Millwall
Docks, London. The ships in which grain is brought to England often
contain a "mixed" cargo as well; and that the unloading of this may
proceed simultaneously with the moving of the wheat it is necessary
to keep the hatches clear. As long as the grain is directly under
a hatchway, a bucket elevator can reach it; but all that is not so
conveniently situated must be brought within range of the buckets. This
means a large bill for labour, even if machinery is employed to help
the "trimming." Mr. Duckham therefore designed an elevator which could
easily reach any corner of a ship's interior. The principal parts are
a large cylindrical air-tight tank, an engine to exhaust air from the
same, and long hoses, armoured inside with a steel lining, connected at
one end to the tank, and furnished at the other with a nozzle. These
hoses extend from the receiving tank to the grain, which, when the air
has been exhausted to five or six pounds to the square inch, flies
up the tubes into the tank. At the bottom of the tank are ingenious
air-locks, to allow the grain to pass into a bin below without
admitting air to spoil the vacuum. The locks are automatic, and as soon
as a certain quantity of grain has collected, tip sideways, closing the
port through which it flowed, and allowing it to drop through a hinged
door. Two locks are attached together, the one discharging while the
other is filling. An elevator of this kind will shift 150 tons or more
an hour. Mr. Duckham claims for his invention that it has no limit in
capacity. It is practically independent of everything but its own steam
power; and the labour of one man suffices to keep its flexible suckers
buried in grain. No corner is inaccessible to the nozzle. The pipes
occupy only a very small part of the hatchway. They can be set to work
immediately a vessel comes alongside. As many as a quarter of a million
bushels are handled daily by one of these machines.

The pneumatic elevator is often installed on a floating base, so that
it may be moved about in a dock.

THE PNEUMATIC BLAST GRAIN-LIFTER

differs from the system just described in that the grain is _driven_
through the pipes or hoses by air compressed to several pounds above
atmospheric pressure. A small tube attached to the main hose conveys
compressed air to the nozzle through which grain enters the tube. The
nozzle consists of a short length of metal piping which is buried
in the grain. One half of it is encased by a jacket into which the
compressed air rushes. As the air escapes at high speed past the inner
end of the piping into the main hose, it causes a vacuum in the piping
and draws in grain, which is shot up the hose by the pressure behind
it. As already remarked, the action of this pneumatic elevator is
similar to that of a steam injector.

THE COMBINED SYSTEM

Under some conditions it is found convenient to employ both suction
and blast in combination: suction to draw the grain from a vessel's
hold into elevators, from which it is transferred to the warehouse by
blast. Special boats are built for this work, _e.g._ the _Garryowen_,
which has on board suction plant for transferring grain from a ship to
barges, and also blowing apparatus for elevating it into storehouses
or into another ship. The _Garryowen_ has the hull and engines of an
ordinary screw steamer, so that it can ply up and down the Shannon and
partly unload a vessel to reduce its draught sufficiently to allow it
to reach Limerick Docks. Floating elevators of this kind are able to
handle upwards of 150 tons of grain per hour.

CHAPTER XVII

MECHANICAL TRANSPORTERS AND CONVEYERS

MECHANICAL CONVEYERS--ROPEWAYS--CABLEWAYS--TELPHERAGE--COALING WARSHIPS
AT SEA

A man carrying a sack of coal over a plank laid from the wharf to the
ship's side, a bricklayer's labourer moving slowly up a ladder with his
hod of mortar--these illustrate the most primitive methods of shifting
material from one spot to another. When the wheelbarrow is used in the
one case, and a rope and pulley in the other, an advance has been made,
but the effort is still great in proportion to the work accomplished;
and were such processes universal in the great industries connected
with mining and manufacture, the labour bill would be ruinous.

The development of methods of transportation has gone on simultaneously
with the improvement of machinery of all kinds. To be successful, an
industry must be conducted economically throughout. Thus, to follow the
history of wheat from the time that it is selected for sowing till it
forms a loaf, we see it mechanically placed in the ground, mechanically
reaped, threshed, and dressed, mechanically hauled to the elevator,
mechanically transferred to the bins of the same, mechanically shot
into trucks or a ship, mechanically raised into a flour-mill, where
it is cleaned, ground, weighed, packed, and trucked by machinery,
mechanically mixed with yeast and baked, and possibly distributed by
mechanically operated vehicles. As a result we get a 2-lb. loaf for
less than three-pence. Anyone who thinks that the price is regulated
merely by the _amount_ of wheat grown is greatly mistaken, for the
cheapness of handling and transportation conduces at least equally to
the cheapness of the finished article.

The same may be said of the metal articles with which every house
is furnished. A fender would be dearer than it is were not the iron
ore cheaply transported from mine to rail, from rail to the smelting
furnace, from the ground to the top of the furnace. In short, to
whatever industry we look, in which large quantities of raw or finished
material have to be moved, stored, and distributed, the mechanical
conveyer has supplanted human labour to such an extent that in lack
of such devices we can scarcely conceive how the industry could be
conducted without either proving ruinous to the people who control it
or enhancing prices enormously.

The types of elevators and conveyers now commonly used in all parts
of the world are so numerous that in the following pages only some
selected examples can be treated.

Speaking broadly, the mechanical transporter can be classified under
two main heads--(1) those which handle materials _continuously_, as in
the case of belt conveyers, pneumatic grain dischargers, etc.; and (2)
those which work _intermittently_, such as the telpher, which carries
skips on an aerial ropeway. The first class are most useful for short
distances; the latter for longer distances, or where the conditions are
such that the material must be transported in large masses at a time by
powerful grabs.

Some transporters work only in a vertical direction; others only
horizontally; while a third large section combine the two movements.
Again, while some are mere conveyers of material shot into or attached
to them, others scoop up their loads as they move. The distinctions in
detail are numerous, and will be brought out in the chapters devoted to
the various types.

MECHANICAL CONVEYERS

We have already noticed band conveyers in connection with the
transportation of grain. They are also used for handling coal, coke,
diamond "dirt," gold ore, and other minerals, and for moving filled
sacks. The belts are sometimes made of rubber or of balata faced with
rubber on the upper surface, which has to stand most of the wear and
tear--sometimes of metal plates joined together by hinges at the ends.

A modification of the belt is the continuous trough, with sloping
or vertical sides. This is built of open-ended sections jointed so
that they may pass round the terminal rollers. While travelling in a
straight line the sides of the sections touch, preventing any escape of
the material carried, but at the rollers the ends open in a V-shape.

Another form of conveyer has a stationary trough through which the
substance to be handled is pulled along by plates attached to cables
or endless chains running on rollers. Or the moving agency may be
plates dragged backwards and forwards periodically, the plates hanging
in one direction only, like flap valves, so as to pass over the
material during the backward stroke, and bite it during the forward
stroke. The vibrating conveyer is a trough which moves bodily backwards
and forwards on hinged supports, the oscillation gradually shaking its
contents along. As no dragging or pushing plates are here needed, this
form of conveyer is very suitable for materials which are liable to be
injured by rough treatment.

ROPEWAYS

A certain person on asking what was the distance from X to Y, received
the reply, "It is ten miles as the crow flies." The country being
mountainous, the answer did not satisfy him, and he said, "Oh! but you
see, I am _not_ a crow." Engineers laying out a railway can sympathise
with this gentleman, for they know from sad experience that places only
a few miles apart in a straight line often require a track many miles
long to connect them if gradients are to be kept moderate.

Now a locomotive, a railway carriage, or a goods truck is very heavy,
and must run on the firm bosom of Mother Earth. But for comparatively
light bodies a path may be made which much more nearly resembles the
proverbial flight of the crow, or, as our American cousins would say, a
bee-line. If you have travelled in Norway and Switzerland you probably
have noticed here and there steel wire ropes spanning a torrent or
hanging across a narrow valley. Over these ropes the peasants shoot
their hay crops or wood faggots from the mountain-side to their homes,
or to a point near a road where the material can be transferred to
carts. Adventurous folk even dare to entrust their own bodies to the
seemingly frail steel thread, using a brake to control the velocity of
the descent.

The history of the modern ropeway and cableway dates from the
'thirties, when the invention of wire rope supplied a flexible carrying
agent of great strength in proportion to its weight, and of sufficient
hardness to resist much wear and tear, and too inelastic to stretch
under repeated stresses. To prevent confusion, we may at once state
that a ropeway is an aerial track used only for the _conveyance_ of
material; whereas a cableway hoists as well as conveys. A further
distinction--though it does not hold good in all cases--may be seen
in the fact that, while cableways are of a single span, ropeways are
carried for distances ranging up to twenty miles over towers or poles
placed at convenient intervals.

Ropeways fall into two main classes: first, those in which the rope
supporting the weight of the thing carried moves; secondly, those in
which the carrier rope is stationary, and the skips, or tubs, etc.,
are dragged along it by a second rope. The moving rope system is best
adapted for light loads, not exceeding six hundredweight or so; but
over the second class bodies scaling five or six tons have often been
moved. In both systems the line may be single or double, according to
the amount of traffic which it has to accommodate. The chief advantage
of the double ropeway is that it permits a continuous service and an
economy of power, since in cases where material has to be delivered
at a lower level than the point at which it is shipped, the weight of
the descending full trucks can be utilised to haul up ascending empty
trucks. Spans of 2,000 feet or two-fifths of a mile are not at all
unusual in very rough country where the spots on which supports can be
erected are few and far between; but engineers naturally endeavour to
make the span as short as possible, in order to be able to use a small
size of rope.

Glancing at some interesting ropeways, we may first notice that used in
the construction of the new Beachy Head Lighthouse, recently erected on
the foreshore below the head on which the original structure stands.
For the sake of convenience, the workshops, storage yards, etc., were
placed on the cliffs, 400 feet above the sea and some 800 feet in a
direct line from the site of the new lighthouse. Between the cliff
summit and a staging in the sea were stretched two huge steel ropes,
the one, six inches in circumference, for the track over which the
four-ton blocks of granite used in the building, machinery, tools,
etc., should be lowered; the other, 5-1/2 inches in circumference, for
the return of the carriers and trucks containing workmen. The ropes had
a breaking strain of 120 and 100 tons respectively; that is to say, if
put in an hydraulic testing machine they would have withstood pulls
equal to those exerted by masses of these weights hung on them. Their
top ends were anchored in solid rock; their lower ends to a mass of
concrete built up in the chalk forming the sea-bottom. When a granite
block was attached to the carrier travelling on the rope, its weight
was gradually transferred to the rope by lowering the truck on which it
had arrived until the latter was clear of the block. As soon as the
stone started on its journey the truck was lifted again to the level of
the rails and trundled away. A brakesman, stationed at a point whence
he could command the whole ropeway, had under his hand the brake wheels
regulating the movements of the trailing ropes for lowering and hauling
on the two tracks.

Another interesting ropeway is that at Hong-Kong, which transports the
workmen in a sugar factory on the low, fever-breeding levels to their
homes in the hills where they may sleep secure from noxious microbes.
The carriers accommodate six men at a time, and move at the rate of
eight miles an hour. The sensation of being hauled through mid-air must
be an exhilarating one, and some of us would not mind changing places
with the workmen for a trip or two, reassured by the fact that this
ropeway has been in operation for several years without any accident.

In Southern India, in the Anamalai Hills, a ropeway is used for
delivering sawn timber from the forests to a point 1-1/4 miles below.
Prior to the establishment of this ropeway the logs were sent down a
circuitous mountain track on bullock carts. Its erection was a matter
of great difficulty, on account of the steep gradients and the dense
and unhealthy forest through which a path had to be cut; not to mention
the dragging uphill of a cable which, with the reel on which it was
wound, weighed four tons. For this last operation the combined strength
of nine elephants and a number of coolies had to be requisitioned,
since the friction of the rope dragging on the ground was enormous.
However, the engineers soon had the cable stretched over its supports,
and the winding machinery in place at the top of the grade. The single
rope serves for both up and down traffic; a central crossing station
being provided at which the descending can pass the ascending carrier.
Seven sleepers at a time are sent flying down the track at a rate of
twenty miles an hour: a load departing every half-hour. The saving of
labour, time, and expense is said to be very great, and when the saw
mills have a larger output the economy of working will be still more
remarkable.

The longest passenger ropeway ever built is probably that over the
Chilkoot Pass in Alaska, which was constructed in 1897 and 1898 to
transport miners from Dyea to Crater Lake on their way to the Yukon
goldfields. From Crater Lake to the Klondike the Yukon River serves
as a natural road, but the climb to its head waters was a matter of
great difficulty, especially during the winter months, and accompanied
by much suffering. But when the trestles had been erected for the
fixed ropes, two in number, miners and their kits were hauled over the
seven miles at little physical cost, though naturally the charges for
transportation ruled higher than in less rugged regions. The opening
of the White Pass Railway from Skagway has largely abolished the need
for this cable track, which has nevertheless done very useful work.
The Chilkoot ropeway has at least two spans of over 1,500 feet. As
an engineering enterprise it claims our consideration, since the
conveyance of ropes, timber, engines, etc., into so inhospitable a
region, and the piecing of them together, demanded great persistence on
the part of the engineers and their employés.

CABLEWAYS

For removing the "over-burden" of surface mines and dumping it in
suitable places, for excavating canals, for dredging, and for many
other operations in which matter has to be moved comparatively short
distances, the cableway is largely employed. We have already noticed
that it differs from the ropeway in that it has to hoist and discharge
its burdens as well as convey them.

The cableway generally consists of a single span between two
towers, which are either fixed or movable on rails according to the
requirements of the work to be done. In addition to the main cable
which bears the weight, and the rope which moves the skips along it,
the cableway has the "fall" rope, which lowers the skip to the ground
and raises it; the dumping rope, which discharges it; and the "button"
rope, which pulls blocks off the horn of the skip truck at intervals as
the latter moves, to support the "fall" rope from the main cable. If
the fall rope sagged its weight would, after a certain amount had been
paid out, overcome the weight of the skip, and render it impossible to
lower the skip to the filling point. So a series of fall-rope carriers
are, at the commencement of a journey from one end of the cableway,
riding on an arm in front of the skip carriage. The button-rope,
passing under a pulley on the top of the skip carriage, is furnished
at intervals with buttons of a size increasing towards the point at
which the skip must be lowered. The holes in the carriers are similarly
graduated so as to pass over any button but the one intended to arrest
them. If we watched a skip travelling to the lowering point, we should
notice that the carriers were successively pulled off the skip carriage
by the buttons, and strung along over the main cable and under the fall
rope.

When the skip has been lowered and filled the fall and hauling ropes
are wound in; the skip rises to the main cable, and begins to travel
towards the dumping point. As long as the dumping rope is also hauled
in at the same rate as the hauling rope it has no effect on the skip,
but when its rate of travel is increased by moving it on to a larger
winding drum, the skip is tipped or opened, as the case may be, without
being arrested.

The skip may be filled by hand or made self-filling where circumstances
permit.

The cableway is so economical in its working that it has greatly
advanced the process of "open-pit" mining. Where ore lies near the
surface it is desirable to remove the useless overlying matter (called
"over-burden") bodily, and to convey it right away, in preference to
sinking shallow shafts with their attendant drawbacks of timbering and
pumping. An inclined railway is handicapped by the fact that it must
occupy some of the surface to be uncovered, while liable to blockage
by the débris of blasting operations. The suspended cableway neither
obstructs anything nor can be obstructed, and is profitably employed
when a ton of ore is laid bare for every four tons of over-burden
removed. In the case of the Tilly Foster Mine, New York, where the
removal of 300,000 tons of rock exposed 600,000 tons of ore from an
excavation 450 ft. long by 300 ft. wide, the saving effected by the
cableway was enormous. Again, referring to the Chicago Drainage Canal,
"the records show that while labourers, sledging and filling into
cars, averaged only 7 to 8-1/2 cubic yards per man per day, in filling
into skips for the cable ways the labourers averaged from 12 to 17
cubic yards per day."[19] The first cableway erected by the Lidgerwood
Manufacturing Company for the prosecution of this engineering work
handled 10,821 cubic yards a month, and proved so successful that
nineteen similar plants were added. The cableways are suspended in this
instance from two towers moving on parallel tracks on each bank of the
canal, the towers being heavily ballasted on the outer sides of their
bases to counteract the pull of the cable. From time to time, when
a length had been cleared, the towers were moved forward by engines
hauling on fixed anchors.

The cableway is much used in the erection of masonry piers for bridges
across rivers or valleys. Materials are conveyed by it rapidly and
easily to points over the piers and lowered into position. Spans of
over 1,500 feet have been exceeded for such purposes; and if need be,
spans of 2,000 feet could be made to carry loads of twenty-five tons at
a rate of twenty miles an hour.

TELPHERAGE

On most ropeways the skips or other conveyances are moved along the
fixed ropes by trailing ropes working round drums driven by steam and
controlled by brakes. But the employment of electricity has provided a
system called _telpherage_, in which the vehicle carries its own motor,
fed by current from the rope on which it runs and from auxiliary
cables suspended a short distance above the main rope. "Telpher" is a
term derived from two Greek words signifying "a far carrier," since the
motor so named will move any distance so long as a track and current
is supplied to it. The carrier--for ore, coal, earth, barrels, sacks,
timber, etc.--is suspended from the telpher by the usual hook-shaped
support common to ropeways, to enable the load to pass the arms of
the posts or trestles bearing the rope. The telpher usually has two
motors, one placed on each side of a two-wheeled carriage so as to
balance; but sometimes only a single motor is employed. Just above the
running cable is the "trolley" cable, from which the telpher picks up
current through a hinged arm, after the manner of an electric tram. The
carriers are controlled on steep grades by an electric braking device,
which acts automatically, its effect varying with the speed at which
the telpher runs. The carrier wheels, driven by the motors, adhere
to the cable without slipping on grades as severe as three in ten,
even when the surface has been moistened by rain. "In order to stop
the telpher at any desired point, the trolley wire is divided into a
number of sections, each controlled by a switch conveniently located.
By opening a switch the current is cut off from the corresponding
section, and the telpher will stop when it reaches this point. It is
again started by closing the switch. At curves a section of the trolley
wire (_i.e._ overhead cable for current) is connected to the source of
current through a 'resistance' which lowers the voltage (pressure of
the current) across the motors at this point. Thus, upon approaching a
curve, the telpher automatically slows down, runs slowly around the
curve until it passes the resistance section, and is then automatically
accelerated."[20]

The telpher line is very useful (for transporting material considerable
distances) in districts where it would not pay to construct a surface
railway. On plantations it serves admirably to shift grain, fruits,
tobacco, and other agricultural products. Then, again, a wide field is
open to it for transmitting light articles, such as castings and parts
of machinery, from one part of a foundry or manufactory to another,
or from factory to vessel or truck for shipment. When coal has to be
handled, the buckets are dumped automatically into bins.

The telpher has much the same advantages over the steam-worked ropeway
that an electric tram has over one moved by an endless cable. Its
control is easier; there is less friction; and the speed is higher. And
in common with ropeways it can claim independence of obstructions on
the ground, and the ability to cross ravines with ease, which in the
case of a railway would have to be bridged at great expense.

COALING WARSHIPS AT SEA

The war between Russia and Japan has brought prominently before the
public the necessity of being able to keep a war vessel well supplied
with coal: a task by no means easy when coaling stations are few and
far between. The voyage of Admiral Rojdestvensky from Russia to Eastern
waters was marked by occasions on which he entered neutral ports to
draw supplies for his furnaces, though we know that colliers sailed
with the warships to replenish their exhausted bunkers. In the
old days of sailing vessels, their motive power, even if fitful, was
inexhaustible. But now that steam reigns supreme as the mover of the
world's floating forts, the problem of "keeping the sea" has become in
one way very much more complicated. The radius of a vessel's action is
limited by the capacity of her coal bunkers. Her captain in war time
would be perpetually perplexed by the question of fuel, since movement
is essential to naval success, while any misjudged fast steaming in
pursuit of the enemy might render his ship an inert mass, incapable
of motion, because the coal supplies had given out; or at least might
compel him to return for supplies to the nearest port at a slow speed,
losing valuable time.

[Illustration: A TEMPERLEY-MILLER MARINE CABLEWAY COALING H.M.S.
"TRAFALGAR" AT SEA

A carrier, from which are slung the sacks of coal, is hauled backwards
and forwards by steel ropes stretching between the foremast of the
transport and a mast rigged on the warship.]

Just as a competitor in a long-distance race takes his nourishment
without halting, so should a battleship be able to coal "on the wing."
The task of transferring so many tons of the mineral from one ship's
hold to that of another may seem easy enough to the inexperienced
critic, and under favourable conditions it might not be attended by
great difficulty. "Why," someone may say, "you have only to bring the
collier alongside the warship, make her fast, and heave out the coals."
In a perfect calm this might be feasible; but let the slightest swell
arise, and then how the sides of the two craft would bump together,
with dire results to the weaker party! Actual tests have shown this.

At present "broadside" coaling is considered impracticable, but the
"from bow to stern" method has passed through its initial stages, and
after many failures has reached a point of considerable efficiency.
The difficulties in transferring coal from a collier to a warship by
which she is being towed will be apparent after very little reflection.
In the first place, there is the danger of the cableway and its load
dipping into the water, should the distance between the two vessels
be suddenly diminished, and the corresponding danger of the cable
snapping should the pitching of the vessels increase the distance
between the terminals of the cableway. These difficulties have made
it impossible to merely shoot coals down a rope attached high up a
mast of the collier and to the deck of the warship. What is evidently
needed is some system which shall pay the cableway out or take it in
automatically, so as to counterbalance any lengthening or shortening
movement of the vessels.

The Lidgerwood Manufacturing Company of New York, under the direction
of Mr. Spencer Miller, have brought out a cableway specially adapted
for marine work. The two vessels concerned are attached by a stout
tow-line, the collier, of course, being in the rear. To carry the load,
a single endless wire rope, 3/8 inch in diameter and 2,000 feet long,
is employed. It spans the distance between collier and ship twice,
giving an inward track for full sacks, and an outward track for their
return to the collier. On one vessel are two winches, the drums of
which both turn in the same direction; but while one drum is rigidly
attached to its axle, the other slips under a stress greater than that
needed to keep the rope sufficiently taut. Since the rope passes round
a pulley at the other terminal, pressure placed at any point on the
rope will tend to tighten both tracks, while a slackening at any point
would similarly ease them. Supposing, then, that the ships suddenly
approach, there will be a certain amount of slack at once wound in; if,
on the other hand, the ships draw apart, the slipping drum will pay
out rope sufficient to supply the need. The constant slipping of this
drum sets up great heat, which is dissipated by currents of air. As the
sacks of coal arrive on the man-of-war they are automatically detached
from the cable, and fall down a chute into the hold.

In the Temperley Miller Marine Cableway the load is carried on a main
cable kept taut by a friction drum, and the hauling is done by an
endless rope which has its own separate winches. In actual tests made
at sea in rough weather sixty tons per hour have been transferred, the
vessels moving at from four to eight miles an hour.

FOOTNOTES:

[19] _Cassier's Magazine._

[20] _Cassier's Magazine._

CHAPTER XVIII

AUTOMATIC WEIGHERS

Scarcely less important than the rapid transference of materials from
one place to another is the quick and accurate weighing of the same. If
a pneumatic grain elevator were used in conjunction with an ordinary
set of scales such as are to be found at a corn dealer's there would be
great delay, and the advantage of the elevator would largely be lost.
Similarly a mechanical transporter of coal or ore should automatically
register the tonnage of the mineral handled, to prevent undue waste of
time.

There are in existence many types of automatic weighing machines, the
general principles of which vary with the nature of the commodity
to be weighed. Finely divided substances, such as grain, seeds, and
sugar, are usually handled by _hopper_ weighers. The grain, etc., is
passed into a bin, from the bottom of which it flows into a large pan.
When the proper unit of weight--a hundredweight or a ton--has nearly
been attained, the flow is automatically throttled, so that it may be
more exactly controlled, and as soon as the full amount has passed,
the machine closes the hopper door and tips the pan over. The latter
delivers its contents and returns to its original position, while the
door above is simultaneously opened for the operation to be repeated.
A counting apparatus records the number of tips, so that a glance
suffices to learn how much material has passed through the weigher,
which may be locked up and allowed to look after itself for hours
together. The "Chronos" automatic grain scale is built in many sizes
for charges of from 12 to 3,300 lbs. of grain, and tips five times a
minute. Avery's grain weigher takes up to 5-1/2 tons at a time.

For materials of a lumpy nature, such as coal and ore, a different
method is generally used. The hopper process would not be absolutely
accurate, since the rate of feed cannot be exactly controlled when dust
and large lumps weighing half a hundredweight or more are all jumbled
together. Therefore instead of a pan which tips automatically as soon
as it has received a fixed weight, we find a bin which, when a quantity
roughly equal to the correct amount has been let in, sinks on to a
weigher and has its contents registered by an automatic counter, which
continuously adds up the total of a number of weighings and displays
it on a dial. So that if there be 10 lbs. in excess of a ton at the
first charge, the dial records "one ton," and keeps the 10 lbs. "up
its sleeve" against the next weighing, to which the excess is added.
Avery's mineral scale works, however, on much the same principle as
that for grain already noticed, a special device being fitted to render
the feed to the weighing pan as regular as possible. His weigher is
used to feed mechanical furnace stokers. The quantity of coal used
can thus be checked, while an automatic apparatus prevents the stoker
bunkers from being overfilled.

_Continuous weighers_ register the amount carried by a conveyer
while in motion. The recording apparatus comes into action at fixed
intervals, _e.g._ as soon as the conveyer has moved ten feet. The
weighing mechanism is practically part of the conveyer, and takes the
weight of ten feet. The steelyard is adjusted to exactly counterbalance
the unloaded belt or skips of its length, but rises in proportion to
the load. As soon as the conveyer has travelled ten feet the weight on
the machine is immediately recorded, and the steelyard returns to zero.

_Intermittent weighers_ record the weight of trucks or tubs passing
over a railway or the cables of aerial track, the weigher forming part
of the track and coming into play as soon as a load is fully on it.

Some machines not only weigh material, but also stow and pack it. We
find a good instance in Timewell's sacking apparatus, which weighs
corn, chaff, flour, oatmeal, rice, coffee, etc., transfers it to sacks,
and _sews the sack up_ automatically. The amount of time saved by such
a machine must be very great.

NOTE.--The author desires to express his indebtedness to Mr. George
F. Zimmer's _The Mechanical Handling of Material_ for some of the
information contained in the above chapter; and to the publishers,
Messrs. A. Crosby Lockwood and Son, for permission to make use of the
same.

CHAPTER XIX

TRANSPORTER BRIDGES

When the writer was in Rouen, in 1898, two lofty iron towers were being
constructed by the Seine: the one on the Quai du Havre, the other on
the Quai Capelier, which borders the river on the side of the suburb
St. Sever.

The towers rose so far towards the sky that one had to throw one's
head very far back to watch the workmen perched on the summit of the
framework. What were the towers for? They seemed much too slender for
the piers of an ordinary suspension bridge fit to carry heavy traffic.
An inquiry produced the information that they were the first instalment
of a "transbordeur," or transporter bridge. What is a bridge of this
kind?

Well, it may best be described as a very lofty suspension bridge, the
girder of which is far above the water to allow the passage of masted
ships. The suspended girder serves only as the run-way for a truck from
which a travelling car hangs by stout steel ropes, the bottom of the
car being but a few feet above the water. The truck is carried across
from tower to tower, either by electric motors or by cables operated by
steam-power.

The transporter bridge in a primitive form has existed for some
centuries, but its present design is of very modern growth. With the
increase of population has come an increased need for uninterrupted
communication. Where rivers intervene they must be bridged, and we see
a steady growth in the number of bridges in London, Paris, New York,
and other large towns.

Unfortunately a bridge, while joining land to land, separates water
from water, and the dislocation of river traffic might not be
compensated by the conveniences given to land traffic. The Forth,
Brooklyn, Saltash, and other bridges have, therefore, been built of
such a height as to leave sufficient head-room under the girders for
the masts of the tallest ships.

But what money they have cost! And even the Tower Bridge, with its
hinged bascules, or leaves, and bridges with centres revolving
horizontally, devour large sums.

Wanted, therefore, an efficient means of transport across a river
which, though not costly to install, shall offer a good service and not
impede river traffic.

Thirty years ago Mr. Charles Smith, a Hartlepool engineer, designed a
bridge of the transporter type for crossing the Tees at Middlesbrough.
The bridge was not built, because people feared that the towers would
not stand the buffets of the north-easterly gales.

The idea promulgated by an Englishman was taken up by foreign
engineers, who have erected bridges in Spain, Tunis, and France.
So successful has this type of ferry-bridge proved, that it is now
receiving recognition in the land of its birth, and at the present time
transporter bridges are nearing completion in Wales and on the Mersey.

[Illustration: THE LATEST TYPE OF BRIDGE

The Transporter Bridge at Bizerta, Tunis. It has a span of 500 feet,
and the suspension girder is 120 feet above high water, so that the
largest vessels may pass under it from the Mediterranean to the inland
lakes. The car is seen near the bottom of the right-hand tower.]

The first "transbordeur" built was that spanning the Nervion, a river
flowing into the Bay of Biscay near Bilbao, a Spanish town famous
for the great deposits of iron ore close by. A pair of towers rises on
each bank to a height of 240 feet, and carry a suspended trussed girder
530 feet long at a level of 150 feet above high-water mark. The car,
giving accommodation for 200 passengers (it does not handle vehicles),
hangs on the end of cables 130 feet long, and is propelled by a
steam-engine situated in one of the towers. Motion is controlled by
the car-conductor, who is connected electrically with the engine-room.
The lofty towers are supported on the landward side by stout steel
ropes firmly anchored in the ground. These ropes are carried over the
girder in the familiar curve of the suspension bridge, and attached
to it at regular intervals by vertical steel braces. The cost of the
bridge--£32,000--compares favourably with that of any alternative
non-traffic-blocking scheme, and the graceful, airy lines of the
erection are by no means a blot on the landscape.

The second "transbordeur" is that of Rouen, already referred to. Its
span is rather less--467 feet--but the suspension girder lies higher
by 14 feet. The car is 42 feet long by 36 broad, and weighs, with a
full load, 60 tons. A passage, which occupies 55 seconds, costs one
penny first class, one halfpenny second class; while a vehicle and
horses pay 2-1/2d. to 4d., according to weight. The car is propelled by
electricity, under the control of a man in the conning-tower perched on
the roof.

At Bizerta we find the third flying-ferry, which connects that town
with Tunis, over a narrow channel between the Mediterranean Sea and two
inland lakes. It replaced a steam-ferry which had done duty for about
ten years.

The lakes being an anchorage for war vessels, it was imperative
that any bridge over the straits should not interrupt free ingress
and egress. This bridge has a span of 500 feet, and like that at
Bilbao is worked by steam. Light as the structure appears, it has
withstood a cyclone which did great damage in the neighbourhood. It is
reported that the French Government has decided to remove the bridge
to some other port, because its prominence would make it serve as a
range-finder for an enemy's cannon in time of war. Its place would be
taken either by a floating-bridge or by a submarine tunnel.

The Nantes "transporter" over the Loire differs from its fellows in one
respect, viz. that it is built on the cantilever or balance principle.
Instead of a single girder spanning the space between the towers,
it has three girders, the two end ones being balanced on the towers
and anchored at their landward extremities by vertical cables. The
gap between them is bridged by a third girder of bow shape, which is
stiff enough in itself to need no central support. The motive power is
electricity.

All these structures will soon be eclipsed by two English bridges: the
one over the Usk at Newport, Monmouthshire; the other over the Mersey
and Manchester Ship Canal at Runcorn "Gap," where the river narrows to
1,200 feet.

The first of these has towers 250 feet high and 685 feet apart. The
girders will give 170 feet head-room above high-water mark. Five
hundred passengers will be able to travel at one time on the car,
besides a number of road vehicles, and as the passage is calculated to
take only one minute, the average velocity will exceed eight miles an
hour. The cost has been set down at £65,000, or about one-thirtieth
that of a suspension bridge, and one-third that of a bascule bridge.
The bridge is being built by the French engineers responsible for the
Rouen _transbordeur_.

Coming to the much more imposing Runcorn bridge we find even these
figures exceeded. This span is 1,000 feet in length. The designer, Mr.
John J. Webster, has already made a name with the Great Wheel which, at
Earl's Court, London, has given many thousands of pleasure-seekers an
aerial trip above the roofs of the metropolis. The following account by
Mr. W. G. Archer in the _Magazine of Commerce_ describes this mammoth
of its kind in some detail:--

"The two main towers carrying the cables and the stiffening girders are
built, one on the south side of the Ship Canal, and the other on the
foreshore on the north bank of the river; and the approaches consist of
new roadways, nearly flat, built between stone and concrete retaining
walls as far as the water's edge, and a corrugated steel flooring,
upon which are laid the timber blocks on concrete, resting on steel
elliptical girders and cast-iron columns. The roadway in front of the
towers is widened out to 70 feet, for marshalling the traffic, and for
providing space for waiting-rooms, etc. The towers are constructed
wholly of steel, rise 190 feet above high-water level, and are bolted
firmly to the cast-iron cylinders below. Each tower consists of four
legs, spaced 30 feet apart at the base, and each pair of towers are
70 feet apart, and are braced together with strong horizontal and
diagonal frames. Each of the two main cables consists of 19 steel ropes
bound together, each rope being built up of 127 wires 0·16 inches in
diameter. The ends of the cable backstays are anchored into the solid
rock on each side of the river, about 30 feet from the rock surface.
The weight of the main cables is about 243 tons, and from them are
suspended two longitudinal stiffening girders, 18 feet deep, and placed
35 feet apart horizontally, the underside of the girders being 82
feet above the level of high water.... Upon the lower flange of the
stiffening girders are fixed the rails upon which runs the traveller,
from which is suspended the car. The traveller is 77 feet long, and is
carried by sixteen wheels on each rail. It is propelled by two electric
motors of about 35 horse-power each.... The car will be capable of
holding at one time four large wagons and 300 passengers, the latter
being protected from the weather by a glazed shelter.... The time
occupied by the car in crossing will be 2-1/4 minutes, so, allowing for
the time spent in loading and unloading, it will be capable of making
nine or ten trips per hour. This bridge, when completed, will have the
largest span of any bridge in the United Kingdom designed for carrying
road traffic, the clear space over the Mersey and Ship Canal being
1,000 feet.... The total cost of the structure, including Parliamentary
expenses, will be about £150,000."

Mr. Archer adds that, in spite of prophecies of disastrous collisions
between transporter cars and passing ships, there has up to date
been no accident of any kind. To those in search of a new sensation
the experience of skimming swiftly a few feet above the water may be
recommended.

CHAPTER XX

BOAT AND SHIP RAISING LIFTS

In modern locomotion, whether by land or water, it becomes increasingly
necessary to keep the way unobstructed where traffic is confined to the
narrow limits of a pair of rails, a road, or a canal channel. We widen
our roads; we double and quadruple our rails. Canals are, as a rule,
not alterable except at immense cost; and if, in the first instance,
they were not built broad enough for the work that they are afterwards
called upon to do, much of their business must pass to rival methods of
transportation. Modern canals, such as the Manchester and Kiel canals,
were given generous proportions to start with, as their purpose was to
pass ocean-going ships, and for many years it will not be necessary to
enlarge them. The Suez Canal has been widened in recent years, by means
of dredgers, which easily scoop out the sandy soil through which it
runs and deposit it on the banks. But the Corinth Canal, cut through
solid rock, cannot be thus economically expanded, and as a result it
has proved a commercial failure.

Even if a canal be of full capacity in its channel-way there are
points at which its traffic is throttled. However gently the country
it traverses may slope, there must occur at intervals the necessity of
making a lock for transferring vessels from one level to the other.
Sometimes the ascent or descent is effected by a series of steps,
or flight of locks, on account of the magnitude of the fall; and in
such cases the loss of time becomes a serious addition to the cost of
transport.

In several instances engineers have got over the difficulty by
ingenious hydraulic lifts, which in a few minutes pass a boat through
a perpendicular distance of many feet. At Anderton, where the Trent
and Mersey Canal meets the Weaver Navigation, barges up to 100 tons
displacement are raised fifty feet. Two troughs, each weighing with
their contents 240 tons, are carried by two cast-iron rams placed
under their centres, the cylinders of which are connected by piping.
When both troughs are full the pressure on the rams is equal, and
no movement results; but if six inches of water be transferred from
the one to the other, the heavier at once forces up the lighter. At
Fontinettes, on the Neufosse Canal, in France, at La Louvière, in
Belgium, and at Peterborough, in Canada, similar installations are
found; the last handling vessels of 400 tons through a rise of 65 feet.

Fine engineering feats as these are, they do not equal the canal-lift
on the Dortmund-Ems Canal, which puts Dortmund in direct water
communication with the Elbe, and opens the coal and iron deposits
of the Rhine and Upper Silesia to the busy manufacturing district
lying between these two localities. About ten miles from its eastern
extremity the main reach of the canal forks off at Heinrichenburg,
from the northward branch running to Dortmund, its level being on
the average some 49 feet lower than the branch. For the transference
of boats an "up" and "down" line of four locks each would have been
needed; and apart from the inevitable two hours' delay for locking,
this method would have entailed the loss of a great quantity of
precious water.

Mr. R. Gerdau, a prominent engineer of Düsseldorf-Grafenburg, therefore
suggested an hydraulic lift, which should accommodate boats of 700
tons, and pass them from the one level to the other in five minutes.

This scheme was approved, and has recently been completed. The
principle of the lift is as follows:--A trough, 233 feet long, rests
on five vertical supports, themselves carried by as many hollow
cylindrical floats moving up and down in deep wells full of water. The
buoyancy of the five floats is just equal to the combined weight of
the trough and its load, so that a comparatively small force causes
the latter to rise or fall, as required. By letting off water from the
trough--which is, of course, furnished with doors to seal its ends--it
would be made to ascend; while the addition of a few tons would cause a
descent. But this would mean waste of water; and, were the trough not
otherwise governed, a serious accident might happen if a float sprang a
leak. Motion is therefore imparted to the trough by four huge vertical
screws, resting on solid masonry piers, and turning in large collars
attached to the trough near its corners. All the screws work in unison
through gearing, as they are sufficiently stout to bear the whole load;
even were the floats removed, no tilting or sudden fall is possible.
The screws are driven by an electric motor of 150 horse-power, perched
on the girders joining the tops of four steel towers which act as
guides for the trough to move in, while they absorb all wind-pressure.
Under normal circumstances the trough rises or sinks at a speed of
four inches per second. The total mass in motion--trough, water, boat,
and floats--is 3,100 tons. Our ideas of a float do not ordinarily rise
above the small cork which we take with us when we go a-fishing, or
at the most above the buoy which bobs up and down to mark a fair-way.
These five "floats"--so called--belong to a very much larger class of
creations. Each is 30 feet across inside and 46-1/2 feet high. Their
wells, 138 feet deep, are lined with concrete nearly a yard thick, to
ensure absolute water-tightness, inside the stout iron casings, which
rise 82 feet above the bottom.

In view of the immense weight which they have to carry, the piers under
the screw-spindles are extremely solid. At its base each measures 14
feet by 12 feet 4 inches, and tapers upwards for 36 feet till these
dimensions have contracted to 8 feet 10 inches by 6 feet 6 inches. The
spindles, 80 feet long and 11 inches in diameter, must be four of the
largest screws in existence. To make it absolutely certain that they
contained no flaws, a 4-inch central hole was drilled through them
longitudinally--another considerable workshop feat. If shafts of such
length were left unsupported when the trough was at its highest point,
there would be danger of their bending and breaking; and they are,
therefore, provided with four sliding collars each, connected each to
its fellow by a rod. When the trough has risen a fifth of its travel
the first rod lifts the first collar, which moves in the guide-pillars.
This in turn raises the second; the second the third; and so on. So
that by the time the trough is fully raised each spindle is kept in
line by four intermediate supports.

The trough, 233 feet long by 34-1/2 feet wide, will receive a vessel
223 feet long between perpendiculars. It has a rectangular section, and
is built up of stout plates laid on strong cross-girders, all carried
by a single huge longitudinal girder resting on the float columns.

One of the most difficult problems inseparable from a structure of
this kind is the provision of a water-tight joint between the trough
and the upper and lower reaches of the canal. At each end of the
trough is a sliding door faced on its outer edges with indiarubber,
which the pressure of the water inside holds tightly against flanges
when pressure on the outside is removed. The termination of the
canal reaches have similar doors; but as it would be impossible to
arrange things so accurately that the two sets of flanges should be
water-tight, a wedge, shaped like a big U, and faced on both sides with
rubber, is interposed. The wedge at the lower reach gate is thickest
at the bottom; the upper wedge the reverse; so that the trough in both
cases jams it tight as it comes to rest. The wedges can be raised or
lowered in accordance with the fluctuations of the canals.

After thus briefly outlining the main constructional features of the
lift, let us watch a boat pass through from the lower to the upper
level. It is a steamer of 600 tons burden, quite a formidable craft
to meet so far inland; while some distance away it blows a warning
whistle, and the motor-man at his post moves a lever which sets the
screw in motion. The trough sinks until it has reached the proper
level, when the current is automatically broken, and it sinks no
further. Its travel is thus controllable to within 3/16 of an inch.

An interlocking arrangement makes it impossible to open the trough
or reach gates until the trough has settled or risen to the level of
the water outside. On the other hand, the motor driving the lifting
screws cannot be started until the gates have been closed, so that an
accidental flooding of the countryside is amply provided against.

A man now turns the crank of a winch on the canal bank and unlocks the
canal gate. A second twist couples the gates between the canal and the
trough together and starts the lifting-motors overhead, which raise the
twenty-eight ton mass twenty-three feet clear of the water-level. The
boat enters; the doors are lowered and uncoupled; the reach gate is
locked. The spindle-motor now starts; up "she" goes, and the process
of coupling and raising gates is repeated before she is released into
the upper reach. From start to finish the transfer occupies about five
minutes.

If a boat is not self-propelled, electric capstans help it to enter and
leave the trough. Such a vessel could not be passed through in less
than twenty minutes.

Putting on one side the ship dry docks, which can raise a 15,000 ton
vessel clear of the sea, the Dortmund hydraulic lift is the largest
lift in the world, and the novelty of its design will, it is hoped,
render the above account acceptable to the reader. Before leaving the
subject another canal lift may be noticed--that on the Grand Junction
Canal at Foxton, Leicestershire--which has replaced a system of ten
locks, to raise barges through a height of 75 feet.

The new method is the invention of Messrs. G. and C. B. J. Thomas.
In principle it consists of an inclined railway, having eight rails,
four for the "up" and as many for the "down" traffic. On each set of
four rails runs a tank mounted on eight wheels, which is connected with
a similar tank on the other set by 7-inch steel-wire ropes passing
round winding drums at the top of the incline. The tanks are thus
balanced. At the foot of the incline a barge which has to ascend is
floated into whichever tank may be ready to receive it, and the end
gate is closed. An engine is then started, and the laden tank slides
"broadside on" up the 300-foot slope. The summit being reached, the
tank gates are brought into register with those of the upper reach,
and as soon as they have been opened the boat floats out into the
upper canal. Boats of 70 tons can be thus transferred in about twelve
minutes, at a cost of but a few pence each. On a busy day 6,000 tons
are handled.

_By permission of_]

[_Mr. Gordon Thomas._

A BOAT LIFT

A canal barge lift which has superseded ten locks at Foxton,
Leicestershire. Two tanks, balancing one another, run on separate
tracks up and down an incline. At the bottom and top of the incline the
tank is submerged so that a barge may float in or out.]

A SHIP-RAISING LIFT

The writer has treated one form of lift for raising ships out of the
water--the floating dry dock--elsewhere,[21] so his remarks in this
place will be confined to mechanism which, having its foundations on
Mother Earth, heaves mighty vessels out of their proper element by
the force of hydraulic pressure. Looking round for a good example of
an hydraulic ship-lift, we select that of the Union Ironworks, San
Francisco.

Some years ago the works were moved from the heart of the city to the
edge of Mission Bay, with the object of carrying on a large business
in marine engineering and shipbuilding. For such a purpose a dry
dock, which in a short time will lift a vessel clear of the water for
cleaning or repairs, is of great importance to both owners and workmen.
By the courtesy of the proprietors of _Cassier's Magazine_ we are
allowed to append the following account of this interesting lift.

The site available for a dock at the Union Ironworks was a mud-flat.
The depth of soft mud being from 80 to 90 feet, would render the
working of a graving dock (_i.e._ one dug out of the ground and pumped
dry when the entrance doors have been closed) very disagreeable; as
such docks, where much mud is carried in with the water, require a long
time to be cleaned and to dry out. Plans were therefore prepared by Mr.
George W. Dickie for an hydraulic dock, including an automatic control,
which the designer felt confident would meet all the requirements
of the situation, and which, after careful consideration, the Union
Ironworks decided to build. Work was begun in January, 1886, and the
dock was opened for business on June 15th, 1887--a very fine record.

This dock consists of a platform built of cross and longitudinal steel
girders, 62 feet wide and 440 feet long, having keel blocks and sliding
bilge blocks upon which the ship to be lifted rests. The lifting power
is generated by a set of four steam-driven, single-acting horizontal
plunger pumps, the diameter of the plungers being 3-1/2 inches and the
stroke 36 inches. Forty strokes per minute is the regular speed.

There is a weighted accumulator, or regulator, connected with the
pumps, the throttle valve of the engines being controlled by the
accumulator.[22] The load on the accumulator consists of a number of
flat discs of metal, the first one about 14 inches thick and the others
about 4 inches thick, the diameter being about 4 feet. The first disc
gives a pressure of 300 lbs. per square inch. This is sufficient to
lift the dock platform without a ship, and is always kept on.

In lifting a ship, as she comes out of the water and gets heavier on
the platform, additional discs are taken on by the accumulator ram as
required. The discs are suspended by pins on the side catching into
links of a chain. The engineer, to take on another disc, unhooks the
throttle from the accumulator rod, runs the engine a little above
the normal speed, the accumulator rises and takes the weight of the
disc to be added; the link carrying that disc is thus relieved and is
withdrawn. The engineer again hooks the accumulator rod to the engine
throttle, and the whole is self-acting again until another weight is
required. When all the discs are on the ram the full pressure of 1,100
lbs. per square inch is reached, which enables a ship of 4,000 tons
weight to be raised.

There are eighteen hydraulic rams on each side of the dock. These rams
are each 30 inches in diameter and have a stroke of 16 feet; and as
the platform rises 2 feet for 1 foot movement of the rams, the total
vertical movement of the platform is 32 feet. When lowered to the
lowest limit there are 22 feet of water over the keel blocks at high
tide.

The foundations consist of seventy-two cylinders of iron, which
extend from the top girders to several feet below the mud line.
These cylinders are driven full of piles, no pile being shorter than
90 feet. The cylinders are to protect the piles from the _teredo_
(the timber-boring worm), which is very destructive in San Francisco
Harbour. A heavy cast-iron cap completes each of the foundation
piers, and two heavy steel girders extend the full length of the dock
on each side, resting on the foundation piers and uniting them all
longitudinally. The hydraulic cylinders are carried by large castings
resting on the girders, each having a central opening to receive a
cylinder, which passes down between the piers. There are thirty-six
foundation piers, and eighteen hydraulic cylinders on each side of the
dock.

On the top of each hydraulic ram is a heavy sheave or pulley, 6 feet
in diameter, over which pass eight steel cables, 2 inches in diameter,
making in all 288 cables. One end of each cable is anchored in the
bed-plates supporting the hydraulic cylinders, while the other end is
secured to the side girders of the platform. Each of the cables has
been tested with a load of 80 tons, so that the total test load for the
ropes has been 21,000 tons.

In lifting a ship the load is never evenly distributed on the platform.
There is, in fact, often more than one ship on the platform at once.
Some rams, therefore, may have a full load and others much less. Under
these conditions, to keep the platform a true plane, irrespective of
the irregular distribution of the load, Mr. Dickie designed a special
valve gear to make the action of the dock perfectly automatic. Down
each side of the dock a shaft is carried, operated by a special engine
in the power house. At each hydraulic ram this shaft carries a worm,
gearing with a worm-wheel on a vertical screw extending the full height
reached by the stroke of the ram. This screw works in a nut on the end
of a lever, the other end of which is attached to the ram. Between the
two points of support a rod, working the valves--also carried by the
ram--engages with the lever. If at a given moment the screw-end is
raised, say, six inches, the lever opens the valve. As the ram rises,
the lever, having its other end similarly lifted by the rise, gradually
assumes a horizontal position, and the valve closes.

To lift the dock the engine working the valve shaft is started, and
with it the operating screws. These, through the levers, open the inlet
valves. The rams now begin to move up: if any one has a light load it
will move up ahead of the other, but in doing so it lifts the other end
of the lever and closes the valve. In fact, the screws are continually
opening the valves, while the motion of the rams is continually closing
them, so that no ram can move ahead of its screw, and the speed of the
screw determines the rate of movement of the lifting platform.

To lower the dock, the engine operating the valve shaft is reversed,
and the screws and levers then control the outlet valves as they
controlled the inlet valves in raising. When the platform has reached
the limit of its movement, a line of locks on top of the foundation
girders, thirty-six on each side, are pushed under the platform by an
hydraulic cylinder, and the platform is lowered on to them, where it
rests until the work is done on the ship; then the platform is again
lifted, the locks are drawn back, and the platform with its load is
lowered until the ship floats out. All the operations are automatic.

Since the dock was opened well over a thousand ships have been lifted
in it without any accident whatever; the total register tonnage
approaching 2,000,000. The great favour in which the dock is held by
shipowners and captains is partly due to the fact already mentioned,
that the ship is lifted above the level of tide water, where the air
can circulate freely under the bottom, thus quickly taking up all the
moisture, and where the workmen can carry on operations with greater
comfort.

When extensive repairs have to be undertaken on iron or steel vessels,
the fact that this dock forms part of an extensive shipbuilding plant,
and is located right in the yard, enables such repairs to be executed
with despatch and economy. Several large steamships have had the
under-water portions of their hulls practically rebuilt in this dock.
The steamship _Columbia_, of the Oregon Line, had practically a new
bottom, including the whole of the keel, completed in twenty-six days.
This is possible, because every facility is alongside the dock and the
bottom of the vessel is on a level with the yard.

This being the only hydraulic dock controlled automatically (in 1897),
it has attracted a large amount of attention from engineering experts
in this class of work. English, French, German, and Russian engineers
have visited the Union Iron Works to study its working, and their
reports have done much to bring the facilities offered to shipping for
repairs by the Union Iron Works to the notice of shipowners all the
world over.

FOOTNOTES:

[21] _The Romance of Modern Engineering_, pp. 383 foll.

[22] For explanation of the "accumulator," see the chapter on Hydraulic
Tools (p. 81).

CHAPTER XXI

A SELF-MOVING STAIRCASE

At the American Exhibition, held in the Crystal Palace in 1902, there
was shown a staircase which, on payment of a penny, transported any
sufficiently daring person from the ground-floor to the gallery above.
All that the experimenters had to do was to step boldly on, take hold
of the balustrade, which moved at an equal pace with the stairs, and
step off when the upper level was reached.

The "escalator" (Latin _scalae_ = flight of stairs) hails from the
United States, where it is proving a serious rival to the elevator. In
principle, it is a continuously working lift, the slow travel of which
is more than compensated by the fact that it is always available. The
ordinary elevator is very useful in a large business or commercial
house, where it saves the legs of people who, if they had to tramp up
flight after flight of stairs, would probably not spend so much money
as they would be ready to part with if their vertical travel from one
floor to another was entirely free of effort. But the ordinary lift is,
like a railway, intermittent. We all know what it means to stand at the
grille and watch the cage slide downwards on its journey of, perhaps,
four floors, when we want to go to a floor higher up. Rather than face
the delay we use our legs.

Theoretically, therefore, a large emporium should contain at least two
lifts. If the number be further increased, the would-be passenger will
have a still better chance of getting off at once. Thus at the station
of the Central London Railway we have to wait but a very few seconds
before a grille is thrown back and an attendant invites us to "Hurry up
there, please!"

Yet there is delay while the cage is being filled. The actual journey
occupies but a small fraction of the time which elapses between the
moment when the first passenger enters the lift at the one end of the
trip and the moment when the last person leaves it at the other end. In
a building where the lift stops every fifteen feet or so to take people
on or put them off, the waste of time is still more accentuated.

The escalator is always ready. You step on and are transported one
stage. A second staircase takes you on at once if you desire it. There
is no delay. Furthermore, the room occupied by a single escalator is
much less than that occupied by the number of lifts required to give
anything like an equally efficient service.

In large American stores, then, it is coming into favour, and also
on the Manhattan Elevated Railway of New York. When once the little
nervousness accompanying the first use has worn off, it eclipses the
lift. A writer in _Cassier's Magazine_ says: "In one large retail store
during the holiday season more than 6,000 persons per hour have been
carried upon the escalator for five hours of the day, and the aggregate
for an entire day is believed to be 50,000. In the same store on an
ordinary day the passengers alighting at the second floor from the
eight large lifts, which run from the basement to the fifth floor, were
counted, likewise the number at the escalator. This latter was found
to be 859 per cent. of the number delivered by the eight lifts. In
another establishment, in a very busy hour, the number taken from the
first floor by the escalator was four times the number taken from the
first floor by the fourteen lifts, which were running at their maximum
capacity. To the merchant this spells opportunity for business.

"The experience at the Twenty-third Street and Sixth Avenue station
of the Manhattan Elevated Railway in New York, during a recent
shut-down of the escalator, which has been in service for some time,
is interesting as showing the attitude of the public, of which many
millions have been carried by the installation during the several years
of its operation. The daily traffic receipts of this station for a
period beginning several weeks before the shut-down and extending as
many after, for the years 1903 and 1902, and receipts of the adjacent
stations for the same period were carefully plotted ... and the loss
area during the period of shut-down was determined. The loss area was
found to embrace 64,645 fares. It was, furthermore, daily a matter of
observation that numbers of people, finding that the escalator was not
running, refused to climb the stairs, and turned away from the station.

"In the case of a great store, the escalator may be constructed as
one continuous machine, with landings at each floor, and so arranged
that steps which carry passengers up may perform a like service in
carrying others down; or separate machines may be installed in various
locations affording the best opportunity for displaying merchandise to
the customer who may be proceeding from the lower to the upper floor.
In the case of a six-storey building so equipped with escalator service
in both directions, or in all ten escalator flights, it is obvious
that the facilities are equal to an impossible number of elevators;
and as facility of access has a direct bearing upon opportunities for
business, it may well be argued that the relative value, measured by
rent, of the main and upper floors is greatly changed."

Each step in a staircase has two parts--the "tread" or horizontal
board on which the foot is placed, and the vertical "riser" which acts
both as a support to the tread above and also prevents the foot from
slipping under the tread. In the escalator each tread is attached
rigidly to its riser, and the two together form an independent unit.

For the convenience of passengers in stepping on or off at the upper
and lower landings, the treads in these places are all in the same
horizontal plane. As they approach the incline the risers gradually
appear, and the treads separate vertically. At the top of the incline
the process is gradually reversed, the risers disappearing until the
treads once more form a horizontal belt.

The means of effecting this change is most ingenious. Each tread and
its riser is carried on a couple of vertical triangular brackets, one
at each side of the staircase. The base of the bracket is uppermost, to
engage with the tread, and its apex has a hole through which passes a
transverse bar, which in its central part forms a pin in the link-chain
by which power is transmitted to the escalator. Naturally, the step
would tip over. This is prevented by a yoke attached to each end of the
bar, at right angles to it and parallel to the tread. The yoke has at
each extremity a small wheel running on its own rail--there being two
rails for each side of the staircase.

Since step, brackets, bar, and yoke are all rigidly joined together,
the step is unable to leave the horizontal, but its relation to the
steps above and below is determined by the arrangement of the rails on
which the yoke wheels run. When these are in the same plane, all the
yokes, and consequently the treads, will also be in the same plane.
But at the incline, where the inner rail gradually sinks lower than
its fellow, the front wheel of one tread is lower than the front wheel
of the next, and the risers appear. It may be added that, owing to the
double track at each side of the staircase, the back wheel of one tread
does not interfere with the front wheel of that below; and that on the
level they come abreast without jostling, as the yoke is bent.

The chain, of which the step-bars form pins, travels under the centre
of the staircase. It is made up of links eighteen inches long, having,
in addition to the bars, a number of steel cross-pins 1-1/2 inches in
diameter, their axes three inches apart, so that the chain as a whole
has a three-inch "pitch." The hubs of the links are bushed with bronze,
and have a graphite "inlay," which makes them self-lubricating. Every
joint is turned to within 1/1,000 inch of absolute accuracy.

The tracks are of steel and hardwood, insulated from the ironwork which
supports them by sheets of rubber. The wheels are so constructed as to
be practically noiseless, so that as a whole the escalator works very
quietly.

"It has been observed," says the authority already quoted, "that
beginners take pains to step upon a single tread, and that after a
little experience no attention whatever is given to the footing, owing
to the facility of adapting oneself to the situation. The upper landing
is somewhat longer, thereby affording an interval for stepping off at
either side of sufficient duration to meet the requirements of the
aged and infirm. The sole function of the travelling landing is to
provide a time interval to meet the requirements of the slowest-acting
passenger, and not of the alert. The terminal of the exit landing, be
it top or bottom (for the escalator operates equally well for either
ascent or descent), is a barrier, called the shunt, of which the lower
member travels horizontally in a plane oblique to the direction of
movement of the steps, and at a speed proportionately greater, thereby
imparting a right-angle resultant to the person or obstacle on the step
which may come in contact with the shunt. By reason of this resultant
motion, the person or obstacle is gently pushed off the end of the
step upon the floor, without shock or injury in the slightest degree.
The motion of the escalator is so smooth and constant that it does not
interpose the least obstacle to the free movement of the passenger, who
may walk in either direction or assume any attitude to the same degree
as upon a stationary staircase."

At Cleveland, U.S.A., there has been erected a rolling roadway,
consisting of an inclined endless belt and platform made of planks
eight feet long, placed transversely across the roadway. The timbers
are fastened together in trucks of two planks each, adjoining trucks
being joined by heavy links to form a moving roadway, which runs on
4,000 small wheels. At each end the roadway, which is continuous,
passes round enormous rollers. Its total length is 420 feet, and the
rise 65 feet. Four electric motors placed at regular intervals along
its length, and all controlled by one man at the head of the incline,
drive it at three miles an hour. It can accommodate six wagons at a
time.

CHAPTER XXII

PNEUMATIC MAIL TUBES

You put your money on the counter. The shop assistant makes out a bill;
and you wonder what he will do with it next. These large stores know
nothing of an open till. Yet there are no cashiers' desks visible; nor
any overhead wires to whisk a carrier off to some corner where a young
lady, enthroned in a box, controls all the pecuniary affairs of that
department.

While you are wondering the assistant has wrapped the coin in the bill
and put the two into a dumb-bell-shaped carrier, which he drops into a
hole. A few seconds later, flop! and the carrier has returned into a
basket under another opening. There is something so mysterious about
the operation that you ask questions, and it is explained to you that
there are pneumatic tubes running from every counter in the building
to a central pay-desk on the first or second floor; and that an engine
somewhere in the basement is hard at work all day compressing air to
shoot the carriers through their tubes.

Certainly a great improvement on those croquet-ball receptacles which
progressed with a deliberation maddening to anyone in a hurry along a
wooden suspended railway! Now, imagine tubes of this sort, only of much
larger diameter, in some cases, passing for miles under the streets
and houses, and you will have an idea of what the Pneumatic Mail
Despatch means: the cash and bill being replaced by letters, telegrams,
and possibly small parcels.

"Swift as the wind" is a phrase often in our mouths, when we wish to
emphasise the celerity of an individual, an animal, or a machine in
getting from one spot of the earth's surface to another. Mercury, the
messenger of uncertain-tempered Jove, was pictured with wings on his
feet to convey, symbolically, the same notion of speed. The modern
human messenger is so poor a counterpart of the god, and his feet are
so far from being winged, that for certain purposes we have fallen
back on elemental air-currents, not unrestrained like the breezes, but
confined to the narrow and certain paths of the metal tube.

The pneumatic despatch, which at the present day is by no means
universal, has been tried in various forms for several decades. Its
first public installation dates from 1853, when a tube three inches
in diameter and 220 yards long was laid in London to connect the
International Telegraph Company with the Stock Exchange. A vacuum
was created artificially in front of the carrier, which the ordinary
pressure of the atmosphere forced through the tube. Soon after this the
post-office authorities took the matter up, as the pneumatic system
promised to be useful for the transmission of letters; but refused to
face the initial expense of laying the tube lines.

When, in 1858, Mr. C. F. Varley introduced the high pressure method,
pneumatic despatch received an impetus comparable to that given to
the steam-engine by the employment of high-pressure steam. It was
now possible to use a double line of tubes economically, the air
compressed for sending the carriers through the one line being pumped
out of a chamber which sucked them back through the other. Tubes for
postal work were soon installed in many large towns in Great Britain,
Europe, and the United States; including the thirty-inch pneumatic
railway between the North-Western District post office in Eversholt
Street and Euston Station, which for some months of 1863 transported
the mails between these two points. The air was exhausted in front of
the carriage by a large fan. Encouraged by its success, the company
built a much larger tube, nearly 4-1/2 feet in diameter, to connect
Euston Station with the General Post Office. This carried fourteen
tons of post-office matter from one end to the other in a quarter
of an hour. There was an intermediate station in Holborn, where the
engines for exhausting had been installed. But owing to the difficulty
of preventing air leakage round the carriages the undertaking proved
a commercial failure, and for years the very route of this pneumatic
railway could not be found; so quickly are "failures" forgotten!

The more useful small tube grew most vigorously in America and France.
In, or about, the year 1875 the Western Union Telegraph Company laid
tubes in New York to despatch telegrams from one part of the city to
the other, because they found it quicker to send them this way than
over the wires. Eighteen years later fifteen miles of tubes were
installed in Chicago to connect the main offices of the same company
with the newspaper offices in the town, and with various important
public buildings. Messages which formerly took an hour or more in
delivery are now flipped from end to end in a few seconds.

The Philadelphia people meanwhile had been busy with a double line of
six-inch tubes, 3,000 feet long, laid by Mr. B. C. Batcheller between
the Bourse and the General Post Office, for the carriage of mails.
The first thing to pass through was a Bible wrapped in the "Stars
and Stripes." A 30 horse-power engine is kept busy exhausting and
compressing the air needed for the service, which amounts to about
800 cubic feet per minute. Philadelphia can also boast an eight-inch
service, connecting the General Post Office with the Union Railway
Station, a mile away. One and a half minutes suffice for the transit of
the large carriers packed tightly with letters and circulars, nearly
half a million of which are handled by these tubes daily.

New York is equally well served. Tubes run from the General Post Office
to the Produce Exchange, to Brooklyn, and to the Grand Central Station.
The last is 3-1/2 miles distant; but seven minutes only are needed
for a tube journey which formerly occupied the mail vans for nearly
three-quarters of an hour.

Paris is the city of the _petit bleu_, so important an institution in
the gay capital. Here a network of tubes connects every post office in
the urban area with a central bureau, acting the part of a telephone
exchange. If you want to send an express message to a friend anywhere
in Paris, you buy a _petit bleu_, _i.e._ a very thin letter-card not
exceeding 1/4 oz. in weight, at the nearest post office, and post it
in a special box. It whirls away to the exchange, and is delivered
from there if its destination be close at hand; otherwise it makes a
second journey to the office most conveniently situated for delivery.
Everybody uses the _voie pneumatique_ of Paris, so much cheaper than,
and quite as expeditious as, the telegraph; with the additional
advantage that all messages are transmitted in the sender's own
handwriting. The system has been instituted for a quarter of a century,
and the Parisians would feel lost without it.

London is by no means tubeless, for it has over forty miles of 1-1/2,
2-1/4, and 3-inch lines radiating from the postal nerve-centre of the
metropolis, of lengths ranging from 100 to 2,000 yards. The tubes are
in all cases composed of lead, enclosed in a protecting iron piping.
To make a joint great care must be exercised, so as to avoid any
irregularity of bore. When a length of piping is added to the line, a
chain is first passed through it, which has at the end a bright steel
mandrel just a shade larger than the pipe's internal diameter. This
is heated and pushed half-way into the pipe already laid; and the new
length is forced on to the other half till the ends touch. A plumber's
joint having been made, the mandrel is drawn by the chain through the
new length, obliterating any dents or malformations in the interior.

The main lines are doubled--an "up" and a "down" track; short branches
have one tube only to work the inward and the outward despatches.

The carriers are made of gutta-percha covered with felt. One end is
closed by felt discs fitting the tube accurately to prevent the passage
of air, the other is open for the introduction of messages. As they fly
through the tube, the carriers work an automatic signalling apparatus,
which tells how far they have progressed and when it will be safe to
despatch the next carrier.

The London post-office system is worked by six large engines situated
in the basement of the General Post Office.

So useful has the pneumatic tube proved that a Bill has been before
Parliament for supplying London with a 12-inch network of tubes,
totalling 100 miles of double line. In a letter published in _The
Times_, April 19, 1905, the promoters of the scheme give a succinct
account of their intentions, and of the benefits which they expect
to accrue from the scheme if brought to completion. The Batcheller
system, they write, with which it is proposed to equip London, is not
a development of the miniature systems used for telegrams or single
letters here or in Paris, Berlin, and other cities. Such systems deal
with a felt carrier weighing a few ounces, which is stopped by being
blown into a box. The Batcheller system deals with a loaded steel
carrier weighing seventy pounds travelling with a very high momentum.
The difference is fundamental. In this sense pneumatic tubes are a
recent invention, and absolutely new to Europe.

The Batcheller system is the response to a pressing need. Careful
observations show that more than 30 per cent. of the street traffic
is occupied with parcels and mails. These form a distinct class,
differentiated from passengers on the one hand and from heavy goods on
the other. The Batcheller system will do for parcels and mails what the
underground electric railways do for passengers. It has been in use for
twelve years in America for mail purposes, and where used has come to
be regarded as indispensable.

The plan for London provides for nearly one hundred miles of double
tubes with about twice that number of stations for receiving and
delivery. The system will cover practically the County of London,
and no point within that area can be more than one-quarter of a mile
from a tube station. Beyond the County of London deliveries will be
made by a carefully organised suburban motor-cart service. Thirty of
the receiving stations are to be established in the large stores. The
diameter of the tube is to be of a size that will accommodate 80 per
cent. of the parcels, as now wrapped, and 90 per cent. with slight
adaptation. The remaining 10 per cent.--furniture, pianos, and other
heavy goods--are to be dealt with by a supplementary motor service.
If the tubes were enlarged their object would be partially defeated,
for with the increased size would go increased cost, great surplus
of capacity, less frequent despatch, and lower efficiency generally.
The unsuccessful Euston Tunnel of forty years ago--practically an
underground railway--is an extreme illustration of this point, though
in that case there were grave mechanical defects as well.

From a mechanical point of view the system has been brought to such
perfection that it is no more experimental than a locomotive or an
electric tramcar. The unique value of tube service is due to immediate
despatch, high velocity of transit, immunity from traffic interruption,
and economy. The greatest obstacle to rapid intercommunication is the
delay resulting from accumulations due to time schedules. The function
of tube service is to abolish time schedules and all consequent delays.

The number of trades parcels annually delivered in London is estimated
at _more than 200,000,000_. A careful canvass has been made of 1,000
shops only, which represent a very small fraction of the total number
in the county. As a result it has been ascertained that these 1,000
shops deliver no fewer than 60,000,000 parcels yearly, a fact that
seems to more than justify the foregoing estimate; on the other hand,
it is known from official data that the parcel post in London is
represented by less than 25,000,000, or one-ninth of the total parcel
traffic. With a tube system in operation, every parcel, instead of
waiting for "the next delivery," would leave the shop immediately.
After being despatched by the tube it would be delivered at a tube
station within a quarter of a mile at least of its destination, and
thence by messenger. The entire time consumed for an ordinary parcel
would be not over an hour, and for a special parcel fifteen to twenty
minutes. They require from three to six hours or longer at present.

The advantages of the tube system to the public would be manifold.
Customers would find their purchases at home upon their return, or,
if they preferred, could do their shopping by telephone, making their
selections from goods sent on approval by tube. The shopman would find
himself relieved from a vast amount of confusion and annoyance, less
of his shop space given up to delivery, and his expenses reduced.
Small shops would be able to draw upon wholesale houses for goods not
in stock, while the customer waited. Such delay and confusion as are
frequently occasioned by fogs would be reduced to a minimum.

While the success of the project is not dependent on Post Office
support, the Post Office should be one of the greatest gainers by it.
The time of delivery of local letters would be reduced from an average
of three hours and six minutes to one hour. Express letters would be
delivered more quickly than telegrams. This has been demonstrated
conclusively again and again in New York and other American cities
where the tubes have been in operation for years. The latest time of
posting country letters would be deferred from one-half to one hour,
and incoming letters would be advanced by a similar period. The parcels
post would gain in precisely the same way, but to an even larger extent.

If the Post Office choose to avail themselves of the opportunity,
every post office will become a tube station and every tube station
a post office. Thus the same number of postmen covering but a tithe
of the present distances could make deliveries without time schedules
at intervals of a few minutes with a handful instead of a bagful of
letters.

The sorting of mails would be performed at every station instead of
at a few. Incoming country mails would be taken from the bags at the
railway termini, and the same bags refilled with outgoing country
mails, thus avoiding needless carriage to the Post Office and back.
No bags at all would be used for local mails, the steel carriers
themselves answering that purpose.

At every tube terminal a post-office clerk would be stationed, so that
the mails would never for an instant be out of post-office control. Its
absolute security would be further ensured by a system of locking, so
that the carriers could only be opened by authorised persons at the
station to which they were directed. These safeguards offer a striking
contrast to the present method that entrusts mail bags to the sole
custody of van drivers in the employ of private contractors.

If the mails were handled by tube, business men would be able to
communicate with each other and receive replies several times in one
day, and country and foreign letters could always be answered upon the
day of receipt. The effect would be felt all over the Empire.

Would the laying of the tubes seriously impede traffic? The promoters
assure us that the inconvenience would not be comparable to that
caused by laying a gas, water, or telephone system. When one of those
has been laid the annoyance, they urge, has only begun. The streets
must be periodically reopened for the purpose of making thousands of
house connections, extensions, and repairs. When a pneumatic tube is
once down it is good for a generation at least. It is not subject to
recurrent alterations incidental to house connections and repairs. In
three American cities the tubes have been touched but three times in
twelve years, and in those cases the causes were a bursting water main
and faulty adjacent electric installations. The repairs were effected
in a few hours.

From a general consideration of the scheme we may now turn to some
mechanical details. The pipes would be of 1 foot internal diameter,
made in 12-foot lengths. "Straight sections," writes an engineering
correspondent of _The Times_, "would be of cast-iron, bored,
counter-bored, and turned to a slight taper at one end, to fit a
recess at the other end (of the next tube), to form the joints, which
could be caulked. Joints made in this way are estimated to permit of
a deflection of 2 inches from the straight, so that the laying and
bedding need not be exact. Bent sections are to be of seamless brass;
these are bored true before bending. The permissible curvature is
determined upon the basis of a _maximum_ bend of 1 foot radius for
every 1 inch of diameter; the 1 foot diameter of the London tubes
would consequently be allowed a _maximum_ curvature of 12 foot radius.
Measured at the enlarged end, the over-all diameter of each pipe is
17 inches, and as two such pipes are to be laid side by side, with
18 inches between centres, the clear width will be 35 inches. The
trenches are therefore to be cut 36 inches wide, and in order to have
a comparatively free run for the sections, it is proposed to cut the
trenches 6 feet deep."

When the hundred miles of piping have been laid, the entire system
will be tested to a pressure of 25 lbs. to the square inch, or about
two and a half times the working pressure. Engines of 10,000 h.p. will
be required to feed the lines with air, for the propulsion of the
carriers, each 3 feet 10 inches long, and weighing 70 lbs.

In order to ensure the delivery of a carrier at its proper destination,
whether a terminus or an intermediate station, Mr. Batcheller has
made a most ingenious provision. On the front of a carrier is fixed a
metal plate of a certain diameter. At each station two electric wires
project into the tube, and as soon as a plate of sufficient diameter
to short-circuit these wires arrives, the current operates delivery
mechanism, and the carrier is switched off into the station box. The
despatcher, knowing the exact size of disc for each station, can
therefore make certain that the carrier shall not go astray.

It may occur to the reader that, should a carrier accidentally stick
anywhere in the tubes, it would be a matter of great difficulty to
locate it. Evidently one could not feel for it with a long rod in half
a mile of tubing--the distance between every two stations--with much
hope of finding it. But science has evolved a simple, and at the same
time quite reliable, method of coping with the problem. M. Bontemps
is the inventor. He located troubles in the Paris tubes by firing
a pistol, and exactly measuring the time which elapsed between the
report and its echo. As the rate of sound travel is definitely known,
instruments of great delicacy enable the necessary calculations to be
made with great accuracy. When a breakdown occurred on the Philadelphia
tube line, Mr. Batcheller employed this method with great success, for
a street excavation, made on the strength of rough measurements with
the timing apparatus, came within a few feet of the actual break in the
pipe, caused by a subsidence, while the carriers themselves were found
almost exactly at the point where the workmen had been told to begin
digging.[23]

There is no doubt that, were such a system as that proposed
established, an enormous amount of time would be saved to the
community. "A letter from Charing Cross to Liverpool Street," says _The
World's Work_, "occupies by post three hours; by tube transit it would
occupy twenty to forty minutes, or by an express system of tube transit
ten to fifteen minutes. Express messages carried by the Post Office in
London last year (1903) numbered about a million and a half, but the
cost sometimes seems very heavy. To send a special message by hand
from Hampstead to Fleet Street, for example, costs 1s. 3d., and takes
about an hour. It is claimed that it could be sent by pneumatic tube
at a cost of 3d. in from fifteen to twenty minutes, and that for local
service the tube would be far quicker than the telegraph, and many
times cheaper."

It has been calculated that from one-sixth to one-quarter of the
wheeled traffic of London is occupied with the distribution of mails
and parcels; and if the tubes relieved the streets to this extent,
this fact alone would be a strong argument in their favour. It is
impossible to believe that tube transmission on a gigantic scale will
not come. Hitherto its development has been hindered by mechanical
difficulties. But these have been mostly removed. In the United States,
where the adage "time is money" is lived up to in a manner scarcely
known on this side of the Atlantic, the device has been welcomed for
public libraries, warehouses, railway depôts, factories--in short,
for all purposes where the employment of human messengers means
delay and uncertainty. Twenty years ago Berlier proposed to connect
London and Paris by tubes of a diameter equal to that of the pipes
contemplated in the scheme now before Parliament. Our descendants may
see the tubes laid; for when once a system of transportation has been
proved efficient on a large scale its development soon assumes huge
proportions. And even the present generation may witness the tubes of
our big cities lengthen their octopus arms till town and town are in
direct communication. After all it is merely a question of "Will it
pay?" We have the _means_ of uniting Edinburgh and London by tube
as effectually as by telephone or telegraph. And since the general
trend of modern commerce is to bring the article to the customer
rather than to give the customer the trouble of going to select the
article _in situ_--this applies, of course, to small portable things
only--"shopping from a distance" will come into greater favour, and the
pneumatic tube will be recognised as a valuable ally. We can imagine
that Mrs. Robinson of, say, Reading, will be glad to be spared the
fatigue of a journey to Regent Street when a short conversation over
the telephone wires is sufficient to bring to her door, within an hour,
a selection of silver ware from which to choose a wedding present. And
her husband, whose car has perhaps broken a rod at Newbury, will be
equally glad of the quick delivery of a duplicate part from the makers.
These are only two possible instances, which do not claim to be typical
or particularly striking. If you sit down and consider what an immense
amount of time and expense could be saved to you in the course of a
year by a "lightning despatch," you will soon come to the conclusion
that the pneumatic tube has a great future before it.

FOOTNOTE:

[23] _Cassier's Magazine_, xiii, 456.

CHAPTER XXIII

AN ELECTRIC POSTAL SYSTEM

Far swifter than the movements of air are those of the electric
current, which travels many thousands of miles in a second of time.

Thirty miles an hour is the speed proposed for the pneumatic tube
system mentioned in our last chapter. An Italian, Count Roberto Taeggi
Piscicelli, has elaborated an electric post which, if realised, will
make such a velocity as that seem very slow motion indeed.

Cable railways, for the transmission of minerals, are in very common
use all over the world. At Hong-Kong and elsewhere they do good service
for the transport of human beings. The car or truck is hauled along
a stout steel cable, supported at intervals on strong poles of wood
or metal, by an endless rope wound off and on to a steam-driven drum
at one end of the line, or motion is imparted to it by a motor, which
picks up current as it goes from the cable itself and other wires with
which contact is made.

Count Piscicelli's electric post is an adaptation of the electric
cableway to the needs of parcel and letter distribution.

At present the mail service between towns is entirely dependent on the
railway for considerable distances, and on motors and horsed vehicles
in cases where only a comparatively few miles intervene. London and
Birmingham, to take an instance, are served by seven despatches each
way every twenty-four hours. A letter sent from London in the morning
would, under the most favourable conditions, not bring an answer
the same day--at least, not during business hours. So that urgent
correspondence must be conducted over either the telephone or the
telegraph wires.

Count Piscicelli proposes a network of light cableways--four lines on
a single set of supports--between the great towns of Britain. Each
line--or rather track--consists of four wires, two above and two below,
each pair on the same level. The upper pair form the run-way for the
two main wheels of the carrier; the lower pair are for the trailing
wheels. Three of the wires supply the three-phase current which drives
the carrier; the fourth operates the automatic switches installed
every three or four miles for transforming the high-tension 5,000-volt
current into low-tension 500-volt current in the section just being
entered.

The carriers would be suitable for letters, book-parcels, and light
packages. The speed at which they would move--150 miles per hour to
begin with--would render possible a ten-minute service between, say,
the towns already mentioned. The inventor has hopes of increasing the
speed to 250 m.p.h., a velocity which would appear visionary had we
not already before us the fact that an electric car, weighing many
tons, has already been sent over the Berlin-Zossen Railway at 131-1/2
miles per hour. At any rate, the electric post can reasonably be
expected to outstrip the ordinary express train. "Should such speeds
as Count Piscicelli confidently discusses," says _The World's Work_,
"be attained, they would undoubtedly confer immense benefits upon the
mercantile and agricultural community--upon the agricultural community
because in this system is to be found that avenue of transmission to
big centres of population of the products of _la petite culture_,
in which Mr. Rider Haggard, for example, in his invaluable book on
_Rural England_, sees help for the farmer and for all connected with
the cultivation of the soil. Count Piscicelli proposes to obviate the
delays at despatching and receiving towns by an inter-urban postal
system, in which the principal offices of any city would be connected
with the head-office and with the principal railway termini. From
each of the sub-offices would radiate further lines, along which
post-collecting pillars are erected, and over which lighter motors and
collecting boxes (similar to the despatch boxes) travel. The letter is
put in through a slot and the stamp cancelled by an automatic apparatus
with the name of the district, number of the post, and time of posting.
The letter then falls into a box at the foot of the column. On the
approach of a collecting-box the letter slot would be closed, and
by means of an electric motor the receptacle containing the letters
lifted to the top of the column and its contents deposited in the
collecting-box, which travels alone past other post-collecting poles,
taking from each its toll, and so on to the district office. Here, in
a mercantile centre, a first sorting takes place, local letters being
retained for distribution by postmen, and other boxes carry their
respective loads to the different railway termini, or central office."

Were such an order of things established, there would be a good excuse
for the old country woman who sat watching the telegraph wire for the
passage of a pair of boots she was sending to her son in far away
"Lunnon"!

CHAPTER XXIV

AGRICULTURAL MACHINERY

PLOUGHS--DRILLS AND SEEDERS--REAPING MACHINES--THRESHING
MACHINES--PETROL-DRIVEN FIELD MACHINERY--ELECTRICAL FARMING
MACHINERY

Agriculture is at once the oldest and most important of all national
industries. Man being a graminivorous animal--witness his molar, or
grinding, "double" teeth--has, since the earliest times, been obliged
to observe the seasons, planting his crops when the ground is moist,
and reaping them when the weather is warm and dry. Apart from the nomad
races of the deserts and steppes, who find their chief subsistence
in the products of the date-palm and of their flocks and herds, all
nations cultivate a large portion of the country which they inhabit.
Ancient monuments, the oldest inscriptions and writings, bear witness
to the prime importance of the plough and reaping-hook; and it may be
reasonably assumed that the progress of civilisation is proved by the
increased use of cereal foods, and better methods of garnering and
preparing them.

For thousands of years the sickle, which Greek and Roman artists placed
in the hand of their Goddess of the Harvest, and the rude plough,
consisting of, perhaps, only a crooked bough with a pointed end, were
practically the only implements known to the husbandman besides his
spade and mattock. Where labour is abundant and each householder has
time to cultivate the little plot which suffices for the maintenance
of his own family, and while there is little inducement to take part
in other than agricultural industries--tedious and time-wasting
methods have held their own. But in highly civilised communities
carrying on manufactures of all sorts it is difficult for the farmer
to secure an abundance of human help, and yet it is recognised that a
speedy preparation and sowing of the land, and a prompt gathering and
threshing of the harvest, is all in favour of producing a successful
and well-conditioned crop.

In England, eighty years ago, three men lived in the country for every
one who lived in the town. Now the proportion has been reversed; and
that not in the British Isles alone. The world does not mean to starve;
but civilisation demands that as few people as possible should be
devoted to procuring the "staff of life" for both man and beast.

We should reasonably expect, therefore, that the immense advance made
in mechanical science during the last century should have left a deep
mark on agricultural appliances. Such an expectation is more than
justified; for are there not many among us who have seen the sickle and
the flail at work where now the "self-binder" and threshing machine
perform the same duties in a fraction of the time formerly required?
The ploughman, plodding sturdily down the furrow behind his clever
team, is indeed still a common sight; but in the tilling season do we
not hear the snort of the steam-engine, as its steel rope tears a
six-furrow plough through the mellow earth? When the harvest comes we
realise even more clearly how largely machinery has supplanted man;
while in the processes of separating the grain from its straw the human
element plays an even smaller part. It would not be too much to say
that, were we to revert next year to the practices of our grandfathers,
we should starve in the year following.

This chapter will be confined to a consideration of machinery
operated by horse, steam, or other power, which falls under four main
headings,--ploughs, drills, reapers, and threshers.

PLOUGHS

The firm of Messrs. John Fowler and Company, of Leeds, is most
intimately connected with the introduction of the steam plough and
cultivator. Their first type of outfit included one engine only, the
traversing of the plough across the field being effected by means of
cables passing round a pulley on a low, four-wheeled truck, moved
along the opposite edge of the field by ropes dragging on an anchor.
Another method was to have the engine stationary at one corner of the
field, and an anchor at each of the three other corners, the two at
the ends of the furrow being moved for every journey of the plough.
In, or about, the year 1865 this arrangement succumbed to the simple
and, as it now seems to us, obvious improvement of introducing a second
engine to progress vis-à-vis with the first, and do its share of the
pulling. The modern eight-furrow steam plough will turn ten acres a
day quite easily, at a much lower cost than that of horse labour. For
tearing up land after a crop "cultivators" are sometimes used. They
have arrowhead-shaped coulters, which cut very deep and bring large
quantities of fresh earth to the surface.

The ground is now pulverised by harrows of various shapes, according
to the nature of the crop to be sown. English farmers generally employ
the spike harrow; but Yankee agriculturists make great use of the
spring-tooth form, which may best be described as an arrangement of
very strong springs much resembling in outline the springs of house
bells. The shorter arm is attached to the frame, while the longer and
pointed arm tears the earth.

DRILLS AND SEEDERS

In highly civilised countries the man carrying a basket from which
he flings seeds broadcast is a very rare sight indeed. The primitive
method may have been effective--a good sower could cover an acre evenly
with half a pint of turnip seed--but very slow. We now use a long bin
mounted on wheels, which revolves discs inside the bin, furnished with
tiny spoons round the periphery to scoop small quantities of seed
into tubes terminating in a coulter. The farmer is thus certain of
having evenly planted and parallel rows of grain, which in the early
spring, when the sprouting begins, make so pleasant an addition to the
landscape.

The "corn," or maize, crop of the United States is so important that
it demands special sowing machinery, which plants single grains at
intervals of about eighteen inches. A somewhat similar device is used
for planting potatoes.

Passing over the weeding machines, which offer no features of
particular interest, we come to the

REAPING MACHINES,

on which a vast amount of ingenuity has been expended. At the beginning
of the nineteenth century the Royal Agricultural Society of Great
Britain offered a prize for the introduction of a really useful machine
which should replace the scythe and sickle. Several machines were
brought out, but they did not prove practical enough to attract much
attention. Cyrus H. McCormick invented in 1831 the reaper, which, with
very many improvements added, is to-day employed in all parts of the
world. The most noticeable point of this machine was the bar furnished
with a row of triangular blades which passed very rapidly to and fro
through slots in an equal number of sharp steel points, against which
they cut the grain. The to-and-fro action of the cutter-blade was
produced by a connecting-rod working on a crank rotated by the wheels
carrying the machine.

[Illustration: A WHEAT-CUTTER

A "heading reaper" being pushed over a wheat crop by six mules. It cuts
off the ears only, leaving the straw standing. The largest machines of
this type used in California take swathes 50 feet broad.]

The first McCormick reaper did wonders on a Virginian farm; other
inventors were stimulated; and in 1833 there appeared the Hussey
reaper, built on somewhat similar lines. For twelve years or so these
two machines competed against one another all over the United States;
and then McCormick added a raker attachment, which, when sufficient
grain had accumulated on the platform, enabled a second man on the
machine to sweep it off to be tied up into a sheaf. At the Great
Exhibition held in London in 1851, the judges awarded a special medal
to the inventor, reporting that the whole expense of the Exhibition
would have been well recouped if only the reaper were introduced into
England. From France McCormick received the decoration of the Legion
of Honour "for having done more for the cause of agriculture than any
man then living."

It would be reasonable to expect that, after this public recognition,
the mechanical reaper would have been immediately valued at its true
worth. "Yet no man had more difficulty in introducing his machines
than that pioneer inventor of agricultural implements. Farmers
everywhere were slow to accept it, and manufacturers were unwilling
to undertake its manufacture. Even after the value of the machine had
been demonstrated, everyone seemed to fear that it would break down
on rocky and uneven fields; and the inventor had to demonstrate in
person to the farmers the practicability of the reapers, and then even
guarantee them before the money could be obtained. Through all these
trying discouragements the persistent inventor passed before he saw any
reward for the work that he had spent half a lifetime in perfecting.
The ultimate triumph of the inventor may be sufficient reward for his
labours and discouragements, but those who would begrudge him the
wealth that he subsequently made from his invention should consider
some of the difficulties and obstacles he had to overcome in the
beginning."[24]

In 1858 an attachment was fitted to replace the second passenger on the
machine. Four men followed behind to tie up the grain as it was shot
off the machine.

Inventors tried to abolish the need for these extra hands by means of a
self-binding device.

A practical method, employing wire, appeared in 1860; but so great was
the trouble caused by stray pieces of the wire getting into threshing
and other machinery through which the grain subsequently passed that
farmers went back to hand work, until the Appleby patent of 1873
replaced wire by twine. Words alone would convey little idea of how the
corn is collected and encircled with twine; how the knot is tied by an
ingenious shuttle mechanism; and how it is thrown out into a set of
arms which collect sufficient sheaves to form a "stook" before it lets
them fall. So we would advise our readers to take the next chance of
examining a modern self-binder, and to persuade the man in charge to
give as lucid an explanation as he can of the way in which things are
done.

Popular prejudice having once been conquered, the success of the
reapers was assured. The year 1870 saw 60,000 in use; by 1885 the
output had increased to 250,000; and to-day the manufacture of
agricultural labour-saving machines gives employment to over 200,000
people; an equal number being occupied in their transport and sale in
all parts of the globe.

In California, perhaps more than in any other country, "power"
agricultural machinery is seen at its best. Great traction-engines
here take the place of human labour to an extraordinary extent. The
largest, of 50 h.p. and upwards, "with driving-wheels 60 inches in
diameter and flanges of generous width, travel over the uneven surface
of the grain fields, crossing ditches and low places, and ascending
the sides of steep hills, with as much apparent ease as a locomotive
rolls along its steel rails. Such powerful traction-engines, or
'automobiles' as they are commonly called by the American farmers, are
capable of dragging behind them sixteen 10-inch ploughs, four 6-foot
harrows, and a drill and seeder. The land is thus ploughed, drilled,
and seeded all at one time. From fifty to seventy-five acres of virgin
soil can thus be ploughed and planted in a single day. When the harvest
comes the engines are again brought into service, and the fields that
would ordinarily defy the best efforts of an army of workmen are
garnered quickly and easily. The giant harvester is hitched to the
traction-engine in place of the ploughs and harrows, and cuts, binds,
and stacks the golden wheat from seventy-five acres in a single day.
The cutters are 26 feet wide, and they make a clear swathe across the
field. Some of them thresh, clean, and sack the wheat as fast as it is
cut and bound. Other traction-engines follow to gather up the sacked
wheat, and whole train-loads of it thus move across the field to the
granaries or railways of the seaboard or interior."

For "dead ripe" crops the "header" is often used in California. Instead
of being pulled it is _pushed_ by mules, and merely cuts off the heads,
leaving the straw to be trampled down by the animals since it has no
value. Swathes as wide as 50 feet are thus treated, the grain being
threshed out while the machine moves.

One of the most beautiful, and at the same time useful, crops in the
world is that of maize, which feeds not only vast numbers of human
beings, but also countless flocks and herds, the latter eating the
green stalks as well as the ripened grain. The United States alone
produced no less than 2,523,648,312 bushels of this cereal in 1902,
as against 987,000,000 bushels of wheat, and 670,000,000 bushels
of barley. Now, maize has a very tough stalk, often 10 feet high
and an inch thick, which cannot be cut with the ease of wheat or
barley. So a special machine has been devised to handle it. The row
of corn is picked up, if fallen, by chains furnished with projecting
spikes working at an angle to the perpendicular, so as to lift and
simultaneously pull back the stalks, which pass into a horizontal
V-shaped frame. This has a broad opening in front, but narrows towards
its rear end, where stationary sickles fixed on either side give the
stalk a drawing cut before it reaches the single knife moving to right
and left in the angle of the V, which severs the stalk completely. The
McCormick machine gathers the corn in vertical bundles, and ties them
up ready for the "shockers."

THRESHING MACHINES

In principle these are simple enough. The straw and grain is fed into
a slot and pulled down between a toothed rotating drum and a fixed
toothed concave. These tear out the grain from the ear. The former