crooked line leaping from one to the other, if not far distant from
each other, only rending the wall in the spaces where these partial
good conductors are too distant from each other.

An iron rod being placed on the outside of a building, from the
highest part continued down into the moist earth, in any direction
strait or crooked, following the form of the roof or other parts of
the building, will receive the lightning at its upper end, attracting
it so as to prevent its striking any other part; and, affording it a
good conveyance into the earth, will prevent its damaging any part of
the building.

A small quantity of metal is found able to conduct a great quantity
of this fluid. A wire no bigger than a goose-quill has been known
to conduct (with safety to the building as far as the wire was
continued) a quantity of lightning that did prodigious damage both
above and below it; and probably larger rods are not necessary,
though it is common in America, to make them of half an inch, some of
three quarters, or an inch diameter.

The rod may be fastened to the wall, chimney, &c. with staples of
iron.--The lightning will not leave the rod (a good conductor) to
pass into the wall (a bad conductor) through those staples.--It would
rather, if any were in the wall, pass out of it into the rod to get
more readily by that conductor into the earth.

If the building be very large and extensive, two or more rods may be
placed at different parts, for greater security.

Small ragged parts of clouds, suspended in the air between the
great body of clouds and the earth (like leaf gold in electrical
experiments) often serve as partial conductors for the lightning,
which proceeds from one of them to another, and by their help comes
within the striking distance to the earth or a building. It therefore
strikes through those conductors a building that would otherwise be
out of the striking distance.

Long sharp points communicating with the earth, and presented to
such parts of clouds, drawing silently from them the fluid they are
charged with, they are then attracted to the cloud, and may leave the
distance so great as to be beyond the reach of striking.

It is therefore that we elevate the upper end of the rod six or eight
feet above the highest part of the building, tapering it gradually to
a fine sharp point, which is gilt to prevent its rusting.

Thus the pointed rod either prevents a stroke from the cloud, or,
if a stroke is made, conducts it to the earth with safety to the
building.

The lower end of the rod should enter the earth so deep as to come
at the moist part, perhaps two or three feet; and if bent when under
the surface so as to go in a horizontal line six or eight feet from
the wall, and then bent again downwards three or four feet, it will
prevent damage to any of the stones of the foundation.

A person apprehensive of danger from lightning, happening during the
time of thunder to be in a house not so secured, will do well to
avoid sitting near the chimney, near a looking glass, or any gilt
pictures or wainscot; the safest place is in the middle of the room
(so it be not under a metal lustre suspended by a chain) sitting in
one chair and laying the feet up in another. It is still safer to
bring two or three mattrasses or beds into the middle of the room,
and, folding them up double, place the chair upon them; for they not
being so good conductors as the walls, the lightning will not chuse
an interrupted course through the air of the room and the bedding,
when it can go through a continued better conductor, the wall. But
where it can be had, a hammock or swinging bed, suspended by silk
cords equally distant from the walls on every side, and from the
cieling and floor above and below, affords the safest situation a
person can have in any room whatever; and what indeed may be deemed
quite free from danger of any stroke by lightning.

  B. FRANKLIN.

  _Paris, Sept. 1767._

FROM J. W.[81] ESQ. PROFESSOR OF NATURAL PHILOSOPHY AT CAMBRIDGE, IN
NEW ENGLAND, JAN. 6, 1768.

  _St. Bride's Steeple.--Utility of Electrical Conductors to
  Steeples.--Singular kind of Glass tube._

"**** I have read in the Philosophical Transactions the account of the
effects of lightning on St. Bride's steeple. It is amazing to me,
that after the full demonstration you had given, of the identity of
lightning and of electricity, and the power of metalline conductors,
they should ever think of repairing that steeple without such
conductors. How astonishing is the force of prejudice even in an age
of so much knowledge and free enquiry!"

ANSWER TO THE ABOVE.

**** It is perhaps not so extraordinary that unlearned men, such as
commonly compose our church vestries, should not yet be acquainted
with, and sensible of the benefits of metal conductors in averting
the stroke of lightning, and preserving our houses from its violent
effects, or that they should be still prejudiced against the use
of such conductors, when we see how long even philosophers, men
of extensive science and great ingenuity, can hold out against
the evidence of new knowledge, that does not square with their
preconceptions; and how long men can retain a practice that is
conformable to their prejudices, and expect a benefit from such
practice, though constant experience shows its inutility. A late
piece of the Abbé Nollet, printed last year in the memoirs of the
French Academy of Sciences, affords strong instances of this: for
though the very relations he gives of the effects of lightning in
several churches and other buildings show clearly, that it was
conducted from one part to another by wires, gildings, and other
pieces of metal that were _within_, or connected with the building,
yet in the same paper he objects to the providing metalline
conductors _without_ the building, as useless or dangerous.[82] He
cautions people not to ring the church bells during a thunder-storm,
lest the lightning, in its way to the earth, should be conducted down
to them by the bell ropes,[83] which are but bad conductors; and yet
is against fixing metal rods on the outside of the steeple, which
are known to be much better conductors, and which it would certainly
chuse to pass in, rather than in dry hemp. And though for a thousand
years past bells have been solemnly consecrated by the Romish
church[84], in expectation that the sound of such blessed bells would
drive away those storms, and secure our buildings from the stroke
of lightning; and during so long a period, it has not been found by
experience, that places within the reach of such blessed sound, are
safer than others where it is never heard; but that on the contrary,
the lightning seems to strike steeples of choice, and that at the
very time the bells are ringing[85]; yet still they continue to bless
the new bells, and jangle the old ones whenever it thunders.--One
would think it was now time to try some other trick;--and ours is
recommended (whatever this able philosopher may have been told to the
contrary) by more than twelve years experience, wherein, among the
great number of houses furnished with iron rods in North America, not
one so guarded has been materially hurt with lightning, and several
have been evidently preserved by their means; while a number of
houses, churches, barns, ships, &c. in different places, unprovided
with rods, have been struck and greatly damaged, demolished or burnt.
Probably the vestries of our English churches are not generally well
acquainted with these facts; otherwise, since as good protestants
they have no faith in the blessing of bells, they would be less
excusable in not providing this other security for their respective
churches, and for the good people that may happen to be assembled
in them during a tempest, especially as those buildings, from their
greater height, are more exposed to the stroke of lightning than our
common dwellings.

I have nothing new in the philosophical way to communicate to you,
except what follows. When I was last year in Germany, I met with a
singular kind of glass, being a tube about eight inches long, half an
inch in diameter, with a hollow ball of near an inch diameter at one
end, and one of an inch and half at the other, hermetically sealed,
and half filled with water.--If one end is held in the hand, and
the other a little elevated above the level, a constant succession
of large bubbles proceeds from the end in the hand to the other
end, making an appearance that puzzled me much, till I found that
the space not filled with water was also free from air, and either
filled with a subtle invisible vapour continually rising from the
water, and extremely rarefiable by the least heat at one end, and
condensable again by the least coolness at the other; or it is the
very fluid of fire itself, which parting from the hand pervades the
glass, and by its expansive force depresses the water till it can
pass between it and the glass, and escape to the other end, where it
gets through the glass again into the air. I am rather inclined to
the first opinion, but doubtful between the two. An ingenious artist
here, Mr. Nairne, mathematical instrument-maker, has made a number
of them from mine, and improved them, for his are much more sensible
than those I brought from Germany.--I bored a very small hole through
the wainscot in the seat of my window, through which a little cold
air constantly entered, while the air in the room was kept warmer
by fires daily made in it, being winter time. I placed one of his
glasses, with the elevated end against this hole; and the bubbles
from the other end, which was in a warmer situation, were continually
passing day and night, to the no small surprise of even philosophical
spectators. Each bubble discharged is larger than that from which
it proceeds, and yet that is not diminished; and by adding itself
to the bubble at the other end, that bubble is not increased, which
seems very paradoxical.--When the balls at each end are made large,
and the connecting tube very small and bent at right angles, so that
the balls, instead of being at the ends, are brought on the side of
the tube, and the tube is held so as that the balls are above it,
the water will be depressed in that which is held in the hand, and
rise in the other as a jet or fountain; when it is all in the other,
it begins to boil, as it were, by the vapour passing up through it;
and the instant it begins to boil, a sudden coldness is felt in the
ball held; a curious experiment, this, first observed and shown me by
Mr. Nairne. There is something in it similar to the old observation,
I think mentioned by Aristotle, that the bottom of a boiling pot is
not warm; and perhaps it may help to explain that fact;--if indeed it
be a fact.--When the water stands at an equal height in both these
balls, and all at rest; if you wet one of the balls by means of a
feather dipt in spirit, though that spirit is of the same temperament
as to heat and cold with the water in the glasses, yet the cold
occasioned by the evaporation of the spirit from the wetted ball will
so condense the vapour over the water contained in that ball, as that
the water of the other ball will be pressed up into it, followed by a
succession of bubbles, till the spirit is all dried away. Perhaps the
observations on these little instruments may suggest and be applied
to some beneficial uses. It has been thought, that water reduced to
vapour by heat was rarefied only fourteen thousand times, and on
this principle our engines for raising water by fire are said to be
constructed: but if the vapour so much rarefied from water is capable
of being itself still farther rarefied to a boundless degree by the
application of heat to the vessels or parts of vessels containing
the vapour (as at first it is applied to those containing the water)
perhaps a much greater power may be obtained, with little additional
expence. Possibly too, the power of easily moving water from one
end to the other of a moveable beam (suspended in the middle like a
scale-beam) by a small degree of heat, may be applied advantageously
to some other mechanical purposes.****

  I am, &c.

  B. FRANKLIN.

FOOTNOTES:

[81] John Winthrop. _Editor._

[82] Notre curiosité pourroit peut-être s'applandir des recherches
qu'elle nous a fait faire sur la nature du tonnerre, & sur la
mécanisme de ses principaux effets, mais ce n'est point ce qu'il y a
de plus important; il vaudroit bien mieux que nous puissions tronver
quelque moyen de nous en garantir: on y a pensé; on s'est même
flatté d'avoir fait cette grande découverte; mais malheureusement
douze années d'épreuves & un peu de réflexion, nous apprennent
qu'il ne faut pas compter sur les promesses qu'on nous a faites. Je
l'ai dit, il y a long temps, and avec regret, toutes ces pointes de
fer qu'on dresse en l'air, soit comme _électroscopes_, soit comme
préservatifs,----sont plus propre à nous attirer le feu du tonnerre
qu'à nous en préserver;----& je persiste â dire que le projet
d'épuiser une nuée orageuse du feu dont elle est chargée, n'est pas
celui d'un physicien,----. _Memoire sur les Effets du Tonnerre._

[83] Les cloches, en vertu de leur bénédiction, doivent écarter les
orages & nous preserver des coups de foudre; mais l'église permet
à la prudence humaine le choix des momens où il convient d'user de
ce préservatif. Je ne sais si le son, considéré physiquement, est
capable ou non de faire crever une nuée, & de causer l'épanchement
de son feu vers les objets terrestres, mais il est certain & prouvé
par l'expérience, que la tonnerre peut tomber sur un clocher, soit
que l'on y sonne ou que l'on n'y sonne point; & si cela arrive dans
le premier cas, les sonneurs sont en grand danger, parcequ'ils
tiennent des cordes par lesquelles la commotion de la foudre peut se
communiquer jusq'à eux: il est donc plus sage de laisser les cloches
en repos quand l'orage est arrivé au-dessus de l'église. Ibid.

[84] Suivant le rituel de Paris, lorsqu'on benit des cloches, on
recite les oraisons suivantes:

_Benedic, Domine ... quotiescumque sonuerit, procul recedat virtus
insidiantium, umbra phantasmatis, incursio turbinum, percussio
fulminum, læsio tonitruum, calamitas tempestatum, omnisque spiritus
procellarum, &c._

_Deus, qui per beatum Moïsen, &c. ... procul pellentur insidiæ
inimici, fragor grandinum, procella turbinum, impetus tempestatum,
temperentur infesta tonitrua. &c._

_Omnipotens sempiterne Deus, &c. ... ut ante sonitum ejus effugentur
ignita jacula inimici, percussio fulminum, impetus lapidum, læsio
tempestatum, &c._

[85] En 1718. M. Deslandes fit savoir à l'Academie Royale des
sciences, que la nuit du 14 ou 15 d'Avril de la mème année, le
tonnerre étoit tombé sur vingtquatre églises, dequis Landernau
jusqu'à Saint-Pol-de-Léon en Bretagne; que ces églises étoient
précisément celles où l'on sonnoit, & que la foudre avoit épargné
celles ou l'on ne sonnoit pas: que dans celle de Gouisnon, qui fut
entièrement ruinée, le tonnerre tua deux personnes de quatre qui
sonnoient, &c. _Hist. du l'Ac. R. des Sci. 1719._

  _Experiments, Observations, and Facts, tending to support the
  Opinion of the Utility of long pointed Rods, for securing Buildings
  from Damage by Strokes of Lightning._

Read at the Committee appointed to consider the erecting Conductors
to secure the Magazines at Purfleet, Aug. 27, 1772.

EXPERIMENT I.

The prime conductor of an electric machine, A. B. (_See Plate_
IV.) being supported about 10 inches and a half above the table by
a wax-stand, and under it erected a _pointed wire_ 7 inches and a
half high, and one-fifth of an inch thick, and tapering to a sharp
point, and communicating with the table; when the _point_ (being
uppermost) is _covered_ by the end of a finger, the conductor may be
full charged, and the electrometer c[86], will rise to the height
indicating a full charge: but the moment the point is _uncovered_,
the ball of the electrometer drops, showing the prime conductor
to be instantly discharged and nearly emptied of its electricity.
Turn the wire its _blunt_ end upwards (which represents an unpointed
bar) and no such effect follows, the electrometer remaining at its
usual height when the prime conductor is charged.

[Illustration: (of these experiments)

  _Plate IV._        _Vol. I. page 388._

_Published as the Act directs, April 1, 1806, by Longman, Hurst, Rees
& Orme, Paternoster Row._]

OBSERVATION.

_What_ quantity of lightning, a high pointed rod well communicating
with the earth may be expected to discharge from the clouds silently
in a short time, is yet unknown; but I have reason from a particular
fact to think it may at some times be very great. In Philadelphia I
had such a rod fixed to the top of my chimney, and extending about
nine feet above it. From the foot of this rod, a wire (the thickness
of a goose-quill) came through a covered glass tube in the roof, and
down through the well of the stair-case; the lower end connected
with the iron spear of a pump. On the stair-case opposite to my
chamber-door, the wire was divided; the ends separated about six
inches, a little bell on each end; [and] between the bells a little
brass ball suspended by a silk thread, to play between and strike
the bells when clouds passed with electricity in them. After having
frequently drawn sparks and charged bottles from the bell of the
upper wire, I was one night waked by loud cracks on the stair-case.
Starting up and opening the door, I perceived that the brass ball,
instead of vibrating as usual between the bells, was repelled and
kept at a distance from both; while the fire passed sometimes in very
large quick cracks from bell to bell; and sometimes in a continued
dense white stream, seemingly as large as my finger, whereby the
whole stair-case was enlightened as with sunshine, so that one
might see to pick up a pin[87]. And from the apparent quantity
thus discharged, I cannot but conceive that a _number_[88] of such
conductors must considerably lessen that of any approaching cloud,
before it comes so near as to deliver its contents in a general
stroke:--An effect not to be expected from bars _unpointed_; if the
above experiment with the blunt end of the wire is deemed pertinent
to the case.

EXPERIMENT II.

The pointed wire under the prime conductor continuing of the same
height, _pinch_ it between the thumb and finger near the top, so as
_just to conceal_ the point; then turning the globe, the electrometer
will rise and mark the full charge. Slip the fingers down so as to
discover about half an inch of the wire, then another half inch, and
then another; at every one of these motions _discovering more and
more_ of the pointed wire; you will see the electrometer fall quick
and proportionably, stopping when you stop. If you slip down the
_whole distance_ at once, the ball falls instantly down to the stem.

OBSERVATION.

From this experiment it seems that a greater effect in drawing off
the lightning from the clouds may be expected from _long_ pointed
rods, than from _short_ ones; I mean from such as show the greatest
length, _above the building_ they are fixed on.

EXPERIMENT III.

Instead of pinching the point between the thumb and finger, as in
the last experiment, keep the thumb and finger each at _near an inch
distance_ from it, but at the _same height_, the point between them.
In this situation, though the point is fairly exposed to the prime
conductor, it has little or no effect; the electrometer rises to
the height of a full charge.--But the moment the fingers are _taken
away_, the ball falls quick to the stem.

OBSERVATION.

To explain this, it is supposed, that one reason of the sudden effect
produced by a long naked pointed wire is, that (by the repulsive
power of the positive charge in the prime conductor) the natural
quantity of electricity contained in the pointed wire is driven down
into the earth, and the point of the wire made strongly _negative_;
whence it attracts the electricity of the prime conductor more
strongly than bodies in their natural state would do; the _small
quantity of common matter_ in the point, not being able by its
attractive force to retain its _natural quantity of the electric
fluid_, against the force of that repulsion.--But the finger and
thumb being substantial and blunt bodies, though as near the prime
conductor, hold up better their _own_ natural quantity against the
force of that repulsion; and so, continuing nearly in the natural
state, they jointly operate on the electric fluid in the point,
opposing its descent, and _aiding the point_ to retain it; contrary
to the repelling power of the prime conductor, which would drive it
down.--And this may also serve to explain the different powers of the
point in the preceding experiment, on the slipping down the finger
and thumb to different distances.

Hence is collected, that a pointed rod erected _between two tall
chimnies_, and very little higher (an instance of which I have seen)
cannot have so good an effect, as if it had been erected on one of
the chimneys, its whole length above it.

EXPERIMENT IV.

If, _instead_ of a long pointed wire, a _large solid body_ (to
represent a building without a point) be brought under and as near
the prime conductor, when charged; the ball of the electrometer will
_fall_ a little; and on taking away the large body, will _rise again_.

OBSERVATION.

Its _rising again_ shows that the prime conductor lost little or
none of its electric charge, as it had done through the point: the
_falling_ of the ball while the large body was under the conductor
therefore shows, that a quantity of its atmosphere was drawn from the
end where the electrometer is placed to the part immediately over the
large body, and there accumulated _ready_ to strike into it with its
whole undiminished force, as soon as within the striking distance;
and, were the prime conductor moveable like a _cloud_, it would
approach the body by attraction till within that distance. The swift
motion of clouds, as driven by the winds, probably prevents this
happening so often as otherwise it might do: for, though parts of
the cloud may stoop towards a building as they pass, in consequence
of such attraction, yet they are carried forward beyond the striking
distance before they could by their descending come within it.

EXPERIMENT V.

Attach a small light _lock of cotton_ to the underside of the
prime conductor, so that it may hang down towards the pointed wire
mentioned in the first experiment. _Cover_ the point with your
finger, and the globe being turned, the cotton will extend itself,
stretching down towards the finger, as at _a_; but on _uncovering_
the point, it instantly flies up to the prime conductor, as at _b_,
and continues there as long as the point is uncovered. The moment
you cover it again, the cotton flies down again, extending itself
towards the finger; and the same happens in degree, if (instead of
the finger) you use, uncovered, the _blunt_ end of the wire uppermost.

OBSERVATION.

To explain this, it is supposed that the cotton, by its connection
with the prime conductor, receives from it a quantity of its
electricity; which occasions its being attracted by the _finger_
that remains still in nearly its natural state. But when a _point_
is opposed to the cotton, its electricity is thereby taken from it,
faster than it can at a distance be supplied with a fresh quantity
from the conductor. Therefore being reduced _nearer_ to the natural
state, it is attracted _up_ to the electrified prime conductor;
_rather than down_, as before, to the finger.

Supposing farther that the prime conductor represents a cloud
charged with the electric fluid; the cotton, a ragged fragment of
cloud (of which the underside of great thunder-clouds are seen to
have many) the finger, a chimney or highest part of a building.--We
then may conceive that when such a cloud passes over a _building_,
some one of its ragged under-hanging fragments may be drawn down
by the chimney or other high part of the edifice; creating thereby
a _more easy communication_ between it and the great cloud.--But a
_long pointed rod_ being presented to this fragment, may occasion
its receding, like the cotton, up to the great cloud; and thereby
_increase_, instead _of lessening_ the distance, so as often to make
it greater than the striking distance. Turning the _blunt end of a
wire_ uppermost (which represents the unpointed bar) it appears that
the same good effect is not from that to be expected. A long pointed
rod it is therefore imagined, may _prevent_ some strokes; as well as
_conduct_ others that fall upon it, when a great body of cloud comes
on so heavily that the above repelling operation on fragments cannot
take place.

EXPERIMENT VI.

Opposite the side of the prime conductor place _separately_, isolated
by wax stems, Mr. Canton's two boxes with pith balls suspended by
fine linen threads. On each box, lay a wire six inches long and
one-fifth of an inch thick, tapering to a sharp point; but so laid,
as that four inches of the _pointed_ end of _one_ wire, and an equal
length of the _blunt_ end of the _other_, may project beyond the ends
of the boxes; and both at eighteen inches distance from the prime
conductor. Then charging the prime conductor by a turn or two of the
globe, the balls of each pair will separate; those of the box, whence
the point projects most, _considerably_; the others _less_. Touch the
prime conductor, and those of the box with the _blunt_ point will
_collapse_, and join. Those connected with the _point_ will at the
same time approach each other, _till_ within about an inch, and there
_remain_.

OBSERVATION.

This seems a proof, that though the small sharpened part of the wire
must have had a _less natural_ quantity in it before the operation,
than the thick blunt part; yet a greater quantity was _driven down
from it_ to the balls. Thence it is again inferred, that the pointed
rod is rendered _more negative_: and farther, that if a _stroke must
fall_ from the cloud over a building, furnished with such a rod,
it is more likely to be drawn to that pointed rod, than to a blunt
one; as being more strongly negative, and of course its attraction
stronger. And it seems more eligible, that the lightning should fall
on the point of the conductor (provided to convey it into the earth)
than on any other part of the building, _thence_ to proceed to such
conductor. Which end is also more likely to be obtained by the length
and loftiness of the rod; as protecting more extensively the building
under it.

It has been _objected_, that erecting pointed rods upon _edifices_,
is to _invite_ and draw the lightning into _them_; and therefore
dangerous. Were such rods to be erected on buildings, _without
continuing the communication_ quite down into the moist earth, this
objection might then have weight; but when such compleat conductors
are made, the lightning is invited not into the building, but into
the _earth_, the situation it aims at, and which it always seizes
every help to obtain, even from broken partial metalline conductors.

It has also been suggested, that from such electric experiments
_nothing certain can be concluded as to the great operations of
nature_; since it is often seen, that experiments, which have
succeeded in small, in large have failed. It is true that in
mechanics this has sometimes happened. But when it is considered
that we owe our first knowledge of the nature and operations of
lightning, to observations on such small experiments; and that on
carefully comparing the most accurate accounts of former facts, and
the exactest relations of those that have occurred since, the effects
have surprizingly agreed with the theory; it is humbly conceived that
in natural philosophy, in this branch of it at least, the suggestion
has not so much weight; and that the farther new experiments now
adduced in recommendation of _long_ sharp-pointed rods, may have some
claim to credit and consideration.

It has been urged too, that though points may have considerable
effects on a _small_ prime conductor at _small distances_; yet on
_great_ clouds and at _great distances_, nothing is to be expected
from them. To this it is answered, that in those _small_ experiments
it is evident the points act at a greater than the _striking_
distance; and in the large way, their service is _only expected_
where there is _such_ nearness of the cloud, as to _endanger a
stroke_; and there, it cannot be doubted the points must have some
effect. And if the quantity discharged by a single pointed rod may
be so considerable as I have shown it; the quantity discharged by a
number will be proportionably greater.

But this part of the theory does not depend alone on _small_
experiments. Since the practice of erecting pointed rods in America
(now near twenty years) five of them have been struck by lightning,
viz. Mr. Raven's and Mr. Maine's in South Carolina; Mr. Tucker's in
Virginia; Mr. West's and Mr. Moulder's in Philadelphia. Possibly
there may have been more that have not come to my knowledge. But in
every one of these, the lightning did _not_ fall upon the _body of
the house_, but precisely on the several _points_ of the rods; and,
though the conductors were sometimes _not sufficiently large and
complete_, was conveyed into the earth, without any material damage
to the buildings. Facts then _in great_, as far as we have them
authenticated, justify the opinion that is drawn from the experiments
_in small_ as above related.

It has also been objected, that unless we knew the quantity that
might _possibly_ be discharged at one stroke from the clouds,
we cannot be sure we have provided _sufficient_ conductors; and
therefore cannot depend on their conveying away _all_ that may fall
on their points. Indeed we have nothing to form a judgment by in
this but past facts; and we know of no instance where a _compleat_
conductor to the moist earth _has_ been insufficient, if half an
inch diameter. It is probable that many strokes of lightning have
been conveyed through the common leaden pipes affixed to houses to
carry down the water from the roof to the ground: and there is no
account of such pipes being melted and destroyed, as must sometimes
have happened if they had been insufficient. We can then only judge
of the dimensions proper for a conductor of lightning, as we do of
those proper for a _conductor of rain_, by past observation. And as
we think a pipe of three inches bore sufficient to carry off the
rain that falls on a square of 20 feet, because we never saw such a
pipe glutted by any shower; so we may judge a conductor of an inch
diameter, more than sufficient for any stroke of lightning that will
fall on its point. It is true that if another deluge should happen
wherein the windows of heaven are to be opened, such pipes may be
unequal to the falling quantity; and if God for our sins should
think fit to rain fire upon us, as upon some cities of old, it is
not expected that our conductors of whatever size, should secure our
houses against a miracle. Probably as water drawn up into the air
and there forming clouds, is disposed to fall again in _rain_ by
its natural gravity, as soon as a number of particles sufficient to
make a drop can get together; so when the clouds are (by whatever
means) over or under-charged [with the _electric fluid_] to a degree
sufficient to attract them towards the earth, the equilibrium is
restored, before the difference becomes great beyond that degree.
Mr. Lane's _electrometer_, for limiting precisely the quantity of
a shock that is to be administered in a medical view, may serve to
make this more easily intelligible. The discharging knob does by a
screw approach the conductor to the distance intended, but there
remains fixed. Whatever power there may be in the glass globe to
collect the fulminating fluid, and whatever capacity of receiving and
accumulating it there may be in the bottle or glass jar; yet neither
the accumulation or the discharge ever exceeds the destined quantity.
Thus, were the _clouds_ always at a certain fixed distance from the
earth, all discharges would be made when the quantity accumulated
was equal to the distance: But there is a circumstance which by
occasionally lessening the distance, lessens the discharge; to wit,
the moveableness of the clouds, and their being drawn nearer to the
earth by attraction when electrified; so that discharges are thereby
rendered more frequent and of course less violent. Hence whatever the
quantity may be in nature, and whatever the power in the clouds of
collecting it; yet an accumulation and force beyond what mankind has
hitherto been acquainted with is scarce to be expected[89].

  B. F.

  _Aug. 27, 1772._

FOOTNOTES:

[86] Mr. Henley's.

[87] Mr. de Romas saw still greater quantities of lightning brought
down by the wire of his kite. He had "explosions from it, the noise
of which greatly resembled that of thunder, and were heard (from
without) into the heart of the city, notwithstanding the various
noises there. The fire seen at the instant of the explosion had the
shape of a spindle eight inches long and five lines in diameter.
Yet from the time of the explosion to the end of the experiment, no
lightning was seen above, nor any thunder heard. At another time the
streams of fire issuing from it were observed to be an inch thick and
ten feet long."--_See Dr. Priestley's History of Electricity_, pages
134-6, _first edition_.

[88] Twelve were proposed on and near the magazines at Purfleet.

[89] It may be fit to mention here, that the immediate occasion of
the dispute concerning the preference between pointed and blunt
conductors of lightning, arose as follows:--A powder-mill having
blown up at Brescia, in consequence of its being struck with
lightning, the English board of ordnance applied to their painter,
Mr. Wilson, then of some note as an electrician, for a method to
prevent the like accident to their magazines at Purfleet. Mr. Wilson
having advised a blunt conductor, and it being understood that Dr.
Franklin's opinion, formed upon the spot, was for a pointed one; the
matter was referred in 1772, to the Royal Society, and by them as
usual, to a committee, who, after consultation, prescribed a method
conformable to Dr. Franklin's theory. But a harmless stroke of
lightning, having under particular circumstances, fallen upon one of
the buildings and its apparatus in May 1777; the subject came again
into violent agitation, and was again referred to the society, and
by the society again referred to a new committee, which committee
confirmed the decision of the first committee.    B. V.[90]

[90] Wherever this signature occurs, the note is taken from a volume
of Dr. Franklin's writings, entitled Political, Miscellaneous, and
Philosophical Pieces, printed for Johnson, 1779. The editor of
that volume, though a young man at the time, had already evinced
extraordinary talents, and was the friend and correspondent of our
author. As he has chosen to withhold his name, we conceive ourselves
not entitled to disclose it: but we shall take the freedom of an
acquaintance to use the notes occasionally, deeming them in many
instances valuable historical records. _Editor._

TO PROFESSOR LANDRIANI, OF ITALY.

  _On the Utility of Electrical Conductors._

  _Philadelphia, Oct. 14, 1787._

  SIR,

I have received the excellent work, _Upon the Utility of electrical
Conductors_, which you had the goodness to send me. I read it with
great pleasure, and beg you to accept my sincere thanks for it.

Upon my return to this country, I found the number of conductors much
increased, many proofs of their efficacy in preserving buildings from
lightning having demonstrated their utility. Among other instances,
my own house was one day attacked by lightning, which occasioned the
neighbours to run in to give assistance, in case of its being on
fire. But no damage was done, and my family was only found a good
deal frightened with the violence of the explosion.

Last year, my house being enlarged, the conductor was obliged to be
taken down. I found, upon examination, that the pointed termination
of copper, which was originally nine inches long, and about one third
of an inch in diameter in its thickest part, had been almost entirely
melted; and that its connection with the rod of iron below was very
slight. Thus, in the course of time, this invention has proved of use
to the author of it, and has added this personal advantage to the
pleasure he before received, from having been useful to others.

Mr. Rittenhouse, our astronomer, has informed me, that having
observed with his excellent telescope, many conductors that are
within the field of his view, he has remarked in various instances,
that the points were melted in like manner. There is no example of
a house, provided with a perfect conductor, which has suffered any
considerable damage; and even those which are without them have
suffered little, since conductors have come common in this city.

  B. FRANKLIN.

TO JOHN PRINGLE, M. D. AND F. R. S.

  _On the Effects of Electricity in paralytic Cases._

  _Craven-street, Dec. 21, 1757._

  SIR,

In compliance with your request, I send you the following account
of what I can at present recollect relating to the effects of
electricity in paralytic cases, which have fallen under my
observation.

Some years since, when the news-papers made mention of great cures
performed in Italy and Germany, by means of electricity, a number of
paralytics were brought to me from different parts of Pensylvania,
and the neighbouring provinces, to be electrised, which I did for
them at their request. My method was, to place the patient first in a
chair, on an electric stool, and draw a number of large strong sparks
from all parts of the affected limb or side. Then I fully charged
two six-gallon glass jars, each of which had about three square feet
of surface coated; and I sent the united shock of these through
the affected limb or limbs, repeating the stroke commonly three
times each day. The first thing observed, was an immediate greater
sensible warmth in the lame limbs that had received the stroke than
in the others; and the next morning the patients usually related,
that they had in the night felt a pricking sensation in the flesh of
the paralytic limbs; and would sometimes show a number of small red
spots, which they supposed were occasioned by those prickings. The
limbs, too, were found more capable of voluntary motion, and seemed
to receive strength. A man, for instance, who could not the first day
lift the lame hand from off his knee, would the next day raise it
four or five inches, the third day higher; and on the fifth day was
able, but with a feeble languid motion, to take off his hat. These
appearances gave great spirits to the patients, and made them hope
a perfect cure; but I do not remember that I ever saw any amendment
after the fifth day; which the patients perceiving, and finding
the shocks pretty severe, they became discouraged, went home, and
in a short time relapsed; so that I never knew any advantage from
electricity in palsies that was permanent. And how far the apparent
temporary advantage might arise from the exercise in the patients
journey, and coming daily to my house, or from the spirits given by
the hope of success, enabling them to exert more strength in moving
their limbs, I will not pretend to say.

Perhaps some permanent advantage might have been obtained, if the
electric shocks had been accompanied with proper medicine and
regimen, under the direction a skilful physician. It may be, too,
that a few great strokes, as given in my method, may not be so proper
as many small ones; since by the account from Scotland of a case, in
which two hundred shocks from a phial were given daily, it seems,
that a perfect cure has been made. As to any uncommon strength
supposed to be in the machine used in that case, I imagine it could
have no share in the effect produced; since the strength of the shock
from charged glass, is in proportion to the quantity of surface of
the glass coated; so that my shocks from those large jars, must have
been much greater than any that could be received from a phial held
in the hand.

  I am, with great respect, Sir,

  Your most obedient Servant,

  B. FRANKLIN.

  _Electrical Experiments on Amber._

  _Saturday, July 3, 1762._

To try, at the request of a friend, whether amber finely powdered
might be melted and run together again by means of the electric
fluid, I took a piece of small glass tube, about two inches and a
half long, the bore about one-twelfth of an inch diameter, the glass
itself about the same thickness; I introduced into this tube some
powder of amber, and with two pieces of wire nearly fitting the
bore, one inserted at one end, the other at the other, I rammed the
powder hard between them in the middle of the tube, where it stuck
fast, and was in length about half an inch. Then leaving the wires in
the tube, I made them part of the electric circuit, and discharged
through them three rows of my case of bottles. The event was, that
the glass was broke into very small pieces and those dispersed with
violence in all directions. As I did not expect this, I had not, as
in other experiments, laid thick paper over the glass to save my
eyes, so several of the pieces struck my face smartly, and one of
them cut my lip a little so as to make it bleed. I could find no
part of the amber; but the table where the tube lay was stained very
black in spots, such as might be made by a thick smoke forced on it
by a blast, and the air was filled with a strong smell, somewhat
like that from burnt gunpowder. Whence I imagined, that the amber
was burnt, and had exploded as gunpowder would have done in the same
circumstances.

That I might better see the effect on the amber, I made the next
experiment in a tube formed of a card rolled up and bound strongly
with packthread. Its bore was about one-eighth of an inch diameter.
I rammed powder of amber into this as I had done in the other, and
as the quantity of amber was greater, I increased the quantity of
electric fluid, by discharging through it at once five rows of my
bottles. On opening the tube, I found that some of the powder had
exploded, an impression was made on the tube, though it was not hurt,
and most of the powder remaining was turned black, which I suppose
might be by the smoke forced through it from the burned part: some of
it was hard; but as it powdered again when pressed by the fingers, I
suppose that hardness not to arise from melting any parts in it, but
merely from my ramming the powder when I charged the tube.

  B. FRANKLIN.

TO THOMAS RONAYNE, ESQ. AT CORKE[91].

  _On the Electricity of the Fogs in Ireland._

  _London, April 20, 1766._

  SIR,

I have received your very obliging and very ingenious letter by
Captain Kearney. Your observations upon the electricity of fogs and
the air in Ireland, and upon different circumstances of storms,
appear to me very curious, and I thank you for them. There is not,
in my opinion, any part of the earth whatever which is, or can be,
naturally in a state of negative electricity: and though different
circumstances may occasion an inequality in the distribution of
the fluid, the equilibrium is immediately restored by means of its
extreme subtilty, and of the excellent conductors with which the
humid earth is amply provided. I am of opinion, however, that when
a cloud, well charged positively, passes near the earth, it repels
and forces down into the earth that natural portion of electricity,
which exists near its surface, and in buildings, trees, &c. so as
actually to reduce them to a negative state before it strikes them.
I am of opinion too, that the negative state in which you have
frequently found the balls, which are suspended from your apparatus,
is not always occasioned by clouds in a negative state; but more
commonly by clouds positively electrified, which have passed over
them, and which in their passage have repelled and driven off a part
of the electrical matter, which naturally existed in the apparatus;
so that what remained after the passing of the clouds, diffusing
itself uniformly through the apparatus, the whole became reduced to a
negative state.

If you have read my experiments made in continuation of those of Mr.
Canton, you will readily understand this; but you may easily make
a few experiments, which will clearly demonstrate it. Let a common
glass be warmed before the fire that it may continue very dry for
some time; set it upon a table, and place upon it the small box made
use of by Mr. Canton, so that the balls may hang a little beyond
the edge of the table. Rub another glass, which has previously been
warmed in a similar manner, with a piece of black silk or a silk
handkerchief, in order to electrify it. Hold then the glass above
the little box, at about the distance of three or four inches from
that part, which is most distant from the balls; and you will see
the balls separate from each other; being positively electrified
by the natural portion of electricity, which was in the box, and
which is driven to the further part of it by the repulsive power of
the atmosphere in the excited glass. Touch the box near the little
balls (the excited glass continuing in the same state) and the balls
will again unite; the quantity of electricity which had been driven
to this part being drawn off by your finger. Withdraw then both
your finger and the glass at the same instant, and the quantity of
electricity which remained in the box, uniformly diffusing itself,
the balls will again be separated; being now in a negative state.
While things are in this situation, begin once more to excite your
glass, and hold it above the box, but not too near, and you will
find, that when brought within a certain distance, the balls will
at first approach each other, being then in a natural state. In
proportion as the glass is brought nearer, they, will again separate,
being positive. When the glass is moved beyond them, and at some
little farther distance, they will unite again, being in a natural
state. When it is entirely removed, they will separate again,
being then made negative. The excited glass in this experiment may
represent a cloud positively charged, which you see is capable of
producing in this manner all the different changes in the apparatus,
without the least necessity for supposing any negative cloud.

I am nevertheless fully convinced, that these are negative clouds;
because they sometimes absorb, through the medium of the apparatus,
the positive electricity of a large jar, the hundredth part of
which the apparatus itself would have not been able to receive or
contain at once. In fact, it is not difficult to conceive, that a
large cloud, highly charged positively, may reduce smaller clouds to
a negative state, when it passes above or near them, by forcing a
part of their natural portion of the fluid either to their inferior
surfaces, whence it may strike into the earth, or to the opposite
side, whence it may strike into the adjacent clouds; so that when
the large cloud has passed off to a distance, the small clouds
shall remain in a negative state, exactly like the apparatus; the
former (like the latter) being frequently insulated bodies, having
communication neither with the earth nor with other clouds. Upon the
same principle it may easily be conceived, in what manner a large
negative cloud may render others positive.

The experiment which you mention, of filing your glass, is analogous
to one which I made in 1751, or 1752. I had supposed in my preceding
letters, that the pores of glass were smaller in the interior parts
than near the surface, and that on this account they prevented the
passage of the electrical fluid. To prove whether this was actually
the case or not, I ground one of my phials in a part where it was
extremely thin, grinding it considerably beyond the middle, and very
near to the opposite superficies, as I found, upon breaking it after
the experiment. It was charged nevertheless after being ground,
equally well as before, which convinced me, that my hypothesis on
this subject was erroneous. It is difficult to conceive where the
immense superfluous quantity of electricity on the charged side of a
glass is deposited.

I send you my paper concerning meteors, which was lately published
here in the Philosophical Transactions, immediately after a paper by
Mr. Hamilton on the same subject.

  I am, Sir, &c.

  B. FRANKLIN.

FOOTNOTE:

[91] This letter is translated from the French edition of Dr.
Franklin's works, as are also all that follow, to the Appendix, the
one to Miss Stephenson excepted. _Editor._

  _Mode of ascertaining, whether the Power, giving a Shock to those
  who touch either the Surinam Eel, or the Torpedo, be electrical._

1. Touch the fish with a stick of dry sealing-wax, or a glass rod,
and observe if the shock be communicated by means of those bodies.

Touch the same fish with an iron, or other metalline rod.

If the shock be communicated by the latter body, and not by the
others, it is probably not the mechanical effect, as has been
supposed, of some muscular action in the fish, but of a subtile
fluid, in this respect analogous at least to the electric fluid.

2. Observe farther, whether the shock can be conveyed without the
metal being actually in contact with the fish, and if it can,
whether, in the space between, any light appear, and a slight noise
or crackling be heard.

If so, these also are properties common to the electric fluid.

3. Lastly, touch the fish with the wire of a small Leyden bottle, and
if the shock can be received across, observe whether the wire will
attract and repel light bodies, and you feel a shock, while holding
the bottle in one hand, and touching the wire with the other.

If so, the fluid, capable of producing such effects seems to have all
the known properties of the electric fluid.

ADDITION, _12th August, 1772,_

  _In Consequence of the Experiments and Discoveries made in France
  by Mr. Walsh, and communicated by him to Dr. Franklin._

Let several persons, standing on the floor, hold hands, and let one
of them touch the fish, so as to receive a shock. If the shock be
felt by all, place the fish flat on a plate of metal, and let one of
the persons holding hands touch this plate, while the person farthest
from the plate touches the upper part of the fish with a metal rod:
then observe, if the force of the shock be the same as to all the
persons forming the circle, or is stronger than before.

Repeat this experiment with this difference: let two or three of the
persons forming the circle, instead of holding by the hand, hold each
an uncharged electrical bottle, so that the little balls at the end
of the wires may touch, and observe, after the shock, if these wires
will attract and repel light bodies, and if a ball of cork, suspended
by a long silk string between the wires, a little distance from the
bottles, will be alternately attracted and repelled by them.

TO M. DUBOURG.

  _On the Analogy between Magnetism and Electricity._

  _London, March 10, 1773._

  SIR,

As to the magnetism, which seems produced by electricity, my real
opinion is, that these two powers of nature have no affinity with
each other, and that the apparent production of magnetism is purely
accidental. The matter may be explained thus:

1st, The earth is a great magnet.

2dly, There is a subtile fluid, called the magnetic fluid, which
exists in all ferruginous bodies, equally attracted by all their
parts, and equally diffused through their whole substance; at least
where the equilibrium is not disturbed by a power superior to the
attraction of the iron.

3dly, This natural quantity of the magnetic fluid, which is contained
in a given piece of iron, may be put in motion so as to be more
rarefied in one part and more condensed in another; but it cannot
be withdrawn by any force that we are yet made acquainted with, so
as to leave the whole in a negative state, at least relatively to
its natural quantity; neither can it be introduced so as to put the
iron into a positive state, or render it _plus_. In this respect,
therefore magnetism differs from electricity.

4thly, A piece of soft iron allows the magnetic fluid which it
contains to be put in motion by a moderate force, so that being
placed in a line with the magnetic pole of the earth, it immediately
acquires the properties of a magnet; its magnetic fluid being drawn
or forced from one extremity to the other; and this effect continues
as long as it remains in the same position, one of its extremities
becoming positively magnetised, and the other negatively. This
temporary magnetism ceases as soon as the iron is turned east and
west, the fluid immediately diffusing itself equally through the
whole iron, as in its natural state.

5thly, The magnetic fluid in hard iron, or steel, is put in motion
with more difficulty, requiring a force greater than the earth to
excite it; and when once it has been forced from one extremity of the
steel to the other, it is not easy for it to return; and thus a bar
of steel is converted into a permanent magnet.

6thly, A great heat, by expanding the substance of this steel, and
increasing the distance between its particles, affords a passage
to the electric fluid, which is thus again restored to its proper
equilibrium; the bar appearing no longer to possess magnetic virtue.

7thly, A bar of steel which is not magnetic, being placed in the same
position, relatively to the pole of the earth, which the magnetic
needle assumes, and in this position being heated and suddenly
cooled, becomes a permanent magnet. The reason is, that while the bar
was hot, the magnetic fluid which it naturally contained was easily
forced from one extremity to the other by the magnetic virtue of the
earth; and that the hardness and condensation, produced by the sudden
cooling of the bar, retained it in this state without permitting it
to resume its original situation.

8thly, The violent vibrations of the particles of a steel bar, when
forcibly struck in the same position, separate the particles in such
a manner during their vibration, that they permit a portion of the
magnetic fluid to pass, influenced by the natural magnetism of the
earth; and it is afterwards so forcibly retained by the re-approach
of the particles when the vibration ceases, that the bar becomes a
permanent magnet.

9thly, An electric shock passing through a needle in a like position,
and dilating it for an instant, renders it, for the same reason, a
permanent magnet; that is, not by imparting magnetism to it, but by
allowing its proper magnetic fluid to put itself in motion.

10thly, Thus, there is not in reality more magnetism in a given
piece of steel after it is become magnetic, than existed in it
before. The natural quantity is only displaced or repelled. Hence it
follows, that a strong apparatus of magnets may charge millions of
bars of steel, without communicating to them any part of its proper
magnetism; only putting in motion the magnetism which already existed
in these bars.

I am chiefly indebted to that excellent philosopher of Petersburgh,
Mr. Æpinus, for this hypothesis, which appears to me equally
ingenious and solid. I say, _chiefly_, because, as it is many years
since I read his book, which I have left in America, it may happen,
that I may have added to or altered it in some respect; and if I have
misrepresented any thing, the error ought to be charged to my account.

If this hypothesis appears admissible, it will serve as an answer to
the greater part of your questions. I have only one remark to add,
which is, that however great the force is of magnetism employed, you
can only convert a given portion of steel into a magnet of a force
proportioned to its capacity of retaining its magnetic fluid in the
new position in which it is placed, without letting it return. Now
this power is different in different kinds of steel, but limited in
all kinds whatever.

  B. FRANKLIN.

TO MESSRS. DUBOURG AND D'ALIBARD[92].

  _Concerning the Mode of rendering Meat tender by Electricity._

  MY DEAR FRIENDS,

My answer to your questions concerning the mode of rendering meat
tender by electricity, can only be founded upon conjecture; for I
have not experiments enough to warrant the facts. All that I can
say at present is, that I think electricity might be employed for
this purpose, and I shall state what follows as the observations or
reasons, which make me presume so.

It has been observed, that lightning, by rarefying and reducing
into vapour the moisture contained in solid wood, in an oak, for
instance, has forcibly separated its fibres, and broken it into small
splinters; that by penetrating intimately the hardest metals, as
iron, it has separated the parts in an instant, so as to convert a
perfect solid into a state of fluidity: it is not then improbable,
that the same subtile matter, passing through the bodies of animals
with rapidity, should possess sufficient force to produce an effect
nearly similar.

The flesh of animals, fresh killed in the usual manner, is firm,
hard, and not in a very eatable state, because the particles adhere
too forcibly to each other. At a certain period, the cohesion is
weakened and in its progress towards putrefaction, which tends to
produce a total separation, the flesh becomes what we call tender, or
is in that state most proper to be used as our food.

It has frequently been remarked, that animals killed by lightning
putrify immediately. This cannot be invariably the case, since a
quantity of lightning sufficient to kill, may not be sufficient to
tear and divide the fibres and particles of flesh, and reduce them to
that tender state, which is the prelude to putrefaction. Hence it is,
that some animals killed in this manner will keep longer than others.
But the putrefaction sometimes proceeds with surprising celerity.
A respectable person assured me, that he once knew a remarkable
instance of this: A whole flock of sheep in Scotland, being closely
assembled under a tree, were killed by a flash of lightning; and
it being rather late in the evening, the proprietor, desirous of
saving something, sent persons early the next morning to flay them;
but the putrefaction was such, and the stench so abominable, that
they had not the courage to execute their orders, and the bodies
were accordingly buried in their skins. It is not unreasonable to
presume, that between the period of their death and that of their
putrefaction, a time intervened in which the flesh might be only
tender, and only sufficiently so to be served at table. Add to this,
that persons, who have eaten of fowls killed by our feeble imitation
of lightning (electricity) and dressed immediately, have asserted,
that the flesh was remarkably tender.

The little utility of this practice has perhaps prevented its being
much adopted. For though it sometimes happens, that a company
unexpectedly arriving at a country-house, or an unusual conflux of
travellers to an inn, may render it necessary, to kill a number
of animals for immediate use; yet as travellers have commonly a
good appetite, little attention has been paid to the trifling
inconvenience of having their meat a little tough. As this kind of
death is nevertheless more sudden, and consequently less severe, than
any other, if this should operate as a motive with compassionate
persons to employ it for animals sacrificed for their use, they may
conduct the process thus:

Having prepared a battery of six large glass jars (each from 20 to
24 pints) as for the Leyden experiment, and having established a
communication, as usual, from the interior surface of each with the
prime conductor, and having given them a full charge (which with a
good machine may be executed in a few minutes, and may be estimated
by an electrometer) a chain which communicates with the exterior of
the jars must be wrapped round the thighs of the fowl; after which
the operator, holding it by the wings, turned back and made to touch
behind, must raise it so high that the head may receive the first
shock from the prime conductor. The animal dies instantly. Let the
head be immediately cut off to make it bleed, when it may be plucked
and dressed immediately. This quantity of electricity is supposed
sufficient for a turkey of ten pounds weight, and perhaps for a
lamb. Experience alone will inform us of the requisite proportions
for animals of different forms and ages. Probably not less will be
required to render a small bird, which is very old, tender, than for
a larger one, which is young. It is easy to furnish the requisite
quantity of electricity, by employing a greater or less number of
jars. As six jars, however, discharged at once, are capable of giving
a very violent shock, the operator must be very circumspect, lest he
should happen to make the experiment on his own flesh, instead of
that of the fowl.

  B. FRANKLIN.

FOOTNOTE:

[92] This letter has no date, but the one to which it is an answer is
dated May 1, 1773. _Editor._

TO M. DUBOURG.

  _In Answer to some Queries concerning the Choice of Glass for the
  Leyden Experiment._

  _London, June 1, 1773._

  SIR,

I wish, with you, that some chemist (who should, if possible, be at
the same time an electrician) would, in pursuance of the excellent
hints contained in your letter, undertake to work upon glass with
the view you have recommended. By means of a perfect knowledge of
this substance, with respect to its electrical qualities, we might
proceed with more certainty, as well in making our own experiments,
as in repeating those, which have been made by others in different
countries, which I believe have frequently been attended with
different success on account of differences in the glass employed,
thence occasioning frequent misunderstandings and contrariety of
opinions.

There is another circumstance much to be desired with respect to
glass, and that is, that it should not be subject to break when
highly charged in the Leyden experiment. I have known eight jars
broken out of twenty, and at another time, twelve out of thirty-five.
A similar loss would greatly discourage electricians desirous of
accumulating a great power for certain experiments.--We have never
been able hitherto to account for the cause of such misfortunes. The
first idea which occurs is, that the positive electricity, being
accumulated on one side of the glass, rushes violently through it, in
order to supply the deficiency on the other side and to restore the
equilibrium. This however I cannot conceive to be the true reason,
when I consider, that a great number of jars being united, so as to
be charged and discharged at the same time, the breaking of a single
jar will discharge the whole; for, if the accident proceeded from the
weakness of the glass, it is not probable, that eight of them should
be precisely of the same degree of weakness, as to break every one
at the same instant, it being more likely, that the weakest should
break first, and, by breaking, secure the rest; and again, when it is
necessary to produce a certain effect, by means of the whole charge
passing through a determined circle (as, for instance, to melt a
small wire) if the charge, instead of passing in this circle, rushed
through the sides of the jars, the intended effect would not be
produced; which, however, is contrary to fact. For these reasons, I
suspect, that there is, in the substance of the glass, either some
little globules of air, or some portions of unvitrified sand or salt,
into which a quantity of the electric fluid may be forced during the
charge, and there retained till the general discharge: and that the
force being suddenly withdrawn, the elasticity of the fluid acts upon
the glass in which it is inclosed, not being able to escape hastily
without breaking the glass. I offer this only as a conjecture, which
I leave to others to examine.

The globe which I had that could not be excited, though it was from
the same glass-house which furnished the other excellent globes
in my possession, was not of the same frit. The glass which was
usually manufactured there, was rather of the green kind, and chiefly
intended for drinking-glasses and bottles; but the proprietors being
desirous of attempting a trial of white glass, the globe in question
was of this frit. The glass not being of a perfect white, the
proprietors were dissatisfied with it, and abandoned their project.
I suspected that too great a quantity of salt was admitted into the
composition; but I am no judge of these matters.

  B. FRANKLIN.

TO MISS STEPHENSON.

  _Concerning the Leyden Bottle._

  _London, March 22, 1762._

I must retract the charge of idleness in your studies, when I find
you have gone through the doubly difficult task of reading so big a
book, on an abstruse subject, and in a foreign language.

In answer to your question concerning the Leyden phial.--The hand
that holds the bottle receives and conducts away the electric fluid
that is driven out of the outside by the repulsive power of that
which is forced into the inside of the bottle. As long as that power
remains in the same situation, it must prevent the return of what it
had expelled; though the hand would readily supply the quantity if it
could be received.

  Your affectionate friend,

  B. FRANKLIN.

APPENDIX.

No. 1[93].

  _The early_ LETTERS _of Dr. Franklin on Electricity having been
  translated into French, and printed at Paris; the Abbé Mazeas, in a
  Letter to Dr. Stephen Hales, dated St. Germain, May 20, 1752, gives
  the following Account (printed in the Philosophical Transactions)
  of the Experiment made at Marly, in Pursuance of that proposed by
  Mr. Franklin, Pages 227, 228._

  SIR,

The Philadelphian experiments, that Mr. Collinson, a member of
the Royal Society, was so kind as to communicate to the public,
having been universally admired in France, the king desired to see
them performed. Wherefore the Duke D'Ayen offered his majesty his
country-house at St. Germain, where M. de Lor, master of experimental
philosophy, should put those of Philadelphia in execution. His
majesty saw them with great satisfaction, and greatly applauded
Messieurs Franklin and Collinson. These applauses of his majesty
having excited in Messieurs de Buffon, D'Alibard, and de Lor, a
desire of verifying the conjectures of Mr. Franklin, upon the
analogy of thunder and electricity, they prepared themselves for
making the experiment.

M. D'Alibard chose for this purpose, a garden situated at Marly,
where he placed upon an electrical body a pointed bar of iron, of
forty feet high. On the 10th of May, twenty minutes past two in
the afternoon, a stormy cloud having passed over the place where
the bar stood, those that were appointed to observe it, drew near,
and attracted from it sparks of fire, perceiving the same kind of
commotions as in the common electrical experiments.

M. de Lor, sensible of the good success of this experiment, resolved
to repeat it at his house in the Estrapade, at Paris. He raised a
bar of iron ninety-nine feet high, placed upon a cake of resin, two
feet square, and three inches thick. On the 18th of May, between four
and five in the afternoon, a stormy cloud having passed over the
bar, where it remained half an hour, he drew sparks from the bar,
like those from the gun barrel, when, in the electrical experiments,
the globe is only rubbed by the cushion, and they produced the same
noise, the same fire, and the same crackling. They drew the strongest
sparks at the distance of nine lines, while the rain, mingled with
a little hail, fell from the cloud, without either thunder or
lightning; this cloud being, according to all appearance, only the
consequence of a storm, which happened elsewhere.

  I am, with a profound respect,

  Your most humble and obedient servant,

  G. MAZEAS.

FOOTNOTE:

[93] See the paragraph between brackets, page 267.

  _A more particular Account of the Circumstances and Success of
  this extraordinary Experiment was laid before the Royal Academy
  of Sciences at Paris, three Days afterwards, in a Memorial by M.
  D'Alibard, viz._

  EXTRAIT D'UN MEMOIRE

  DE M. D'ALIBARD,

  _Lû à l'Académie Royale des Sciences, le 13 Mai, 1752._

"En suivant la route que M. Franklin nous a tracée, j'ai obtenu une
satisfaction complette. Voici les préparatifs, le procédé & le succès.

"1º. J'ai fait faire à Marly-la-ville, située à six lieues de Paris
au milieu d'une belle plaine dont le sol est fort élevé, une verge de
fer ronde, d'environ un pouce de diametre, longue de 40 pieds, & fort
pointue par son extrémité supérieure; pour lui ménager une pointe
plus fine, je l'ai fait armer d'acier trempé & ensuite brunir, au
défaut de dorure, pour la préserver de la rouille; outre cela, cette
verge de fer est courbée vers son extrémité inférieure en deux coudes
à angles aigus quoiqu'arrondis; le premier coude est éloigné de deux
pieds du bout inférieur, & le second est en sens contraire à trois
pieds du premier.

"2º. J'ai fait planter dans un jardin trois grosses perches de 28
à 29 pieds, disposées en triangle, & éloignées les unes des autres
d'environ huit pieds; deux de ces perches sont contre un mur, &
la troisieme est au-dedans du jardin. Pour les affermir toutes
ensemble, l'on à cloué sur chacune des entretoises à vingt pieds de
hauteur; & comme le grand vent agitoit encore cette espéce d'édifice,
l'on a attaché au haut de chaque perche de longs cordages, qui tenant
lieu d'aubans, répondent par le bas à de bons piquets fortement
enfoncés en terre à plus de 20 pieds des perches.

"3º. J'ai fait construire entres les deux perches voisines du mur, &
adosser contre ce mur une petite guerite de bois capable de contenir
un homme & une table.

"4º. J'ai fait placer au milieu de la guérite une petite table
d'environ un demi-pied de hauteur; & sur cette table j'ai fait
dresser & affermir un tabouret electrique. Ce tabouret n'est autre
chose qu'une petite planche quarrée, portée sur trois bouteilles à
vin; il n'est fait de cette matiere que pour suppléer au defaut d'un
gâteau de résine qui me manquoit.

"5º. Tout étant ainsi préparé, j'ai fait elever perpendiculairement
la verge de fer au milieu des trois perches, & je l'ai affermie en
l'attachant à chacune des perches avec de forts cordons de soie par
deux endroits seulement. Les premiers liens sont au haut des perches,
environ trois pouces au-dessous de leurs extrémités supérieures; les
seconds vers la moitié de leur hauteur. Le bout inférieur de la verge
de fer est solidement appuyé sur le milieu du tabouret electrique, où
j'ai fait creuser un trou propre à le recevoir.

"6º. Comme il étoit important de garantir de la pluie te tabouret
& les cordons de soie, parce qu'ils laisseroient passer la matiére
électrique s'ils etoient mouillés, j'ai pris les précautions
necessaires pour en empêcher. C'est dans cette vue que j'ai mis mon
tabouret sous la guérite, & que j'avois fait courber ma verge de fer
à angles aigus; afin que l'eau qui pourroit couler le long de cette
verge, ne pût arriver jusques sur le tabouret. C'est aussi dans le
même dessein que j'ai fait clouer sur le haut & au milieu de mes
perches, à trois pouces au-dessus des cordons de soie, des especes de
boîtes formées de trois petites planches d'environ 15 pouces de long,
qui couvrent par-dessus & par les côtes une pareille longueur des
cordons de soie, sans leur toucher.

"Il s'agissoit de faire, dans le tems de l'orage, deux observations
sur cette verge de fer ainsi disposée; l'une étoit de remarquer à sa
pointe une aigrette lumineuse, semblable à celle que l'on apperçoit
à la pointe d'une aiguille, quand on l'oppose assez près d'un corps
actuellement électrisé; l'autre étoit de tirer de la verge de fer des
étincelles, comme on en tire du canon de fusil dans les expériences
électriques; & afin de se garantir des piqûres de ces étincelles,
j'avois attaché le tenon d'un fil d'archal au cordon d'une longue
fiole pour lui servir de manche....

"Le Mercredi 10 Mai 1752, entre deux & trois heures après midi,
le nommé Coiffier, ancien dragon, que j'avois chargé de faire les
observations en mon absence, ayant entendu un coup de tonnerre
assez fort, vole aussitôt à la machine, prend la fiole avec le fil
d'archal, présente le tenon du fil à la verge, en voit sortir une
petite étincelle brillante, & en entend le pétillement; il tire une
seconde étincelle plus fort que la premiere & avec plus de bruit! il
appelle ses voisins, & envoie chercher M. le Prieur. Celui-ci accourt
de toutes ses forces; les paroissiens voyant la précipitation de
leur curé, s'imaginent que le pauvre Coiffier a été tué du tonnerre;
l'allarme se répand dans le village: la grêle qui survient n'empêche
point le troupeau du suivre son pasteur. Cet honnête ecclésiastique
arrive près de la machine, & voyant qu'il n'y avoit point de danger,
met lui-même la main â l'oeuvre & tire de fortes étincelles. La
nuée d'orage & de grêle ne fut pas plus d'un quart-d'heure à passer
au zénith de notre machine, & l'on n'entendit que ce seul coup
de tonnerre. Sitôt que le nuage fut passé, & qu'on ne tira plus
d'étincelles de la verge de fer, M. le Prieur de Marly fit partir le
sieur Coiffier lui-même, pour m'apporter la lettre suivante, qu'il
m'ecrivit à la hâte."

_Je vous annonce, Monsieur, ce que veus attendez: l'expérience est
complette. Aujourd'hui à deux heures 20 minutes après midi, le
tonnerre a grondé directement sur Marly; le coup a été assez fort.
L'envie de vous obliger, & la curiosité m'ont tiré de mon fauteüil,
où j'êtois occupé à lire: je suis allé chez Coiffier, qui déja
m'avoit dépêché un enfant que j'ai rencontré en chemin, pour me prier
de veenir; j'ai doublé le pas à travers un torrent de grêle. Arrivé
à l'endroit où est placée la tringle coudée, j'ai présenté le fil
d'archal, en evançant successivement vers la tringle, à un pouce &
demi, ou environ; il est sorti de la tringle une petite colonne de
fer bleuâtre sentant le soufre, qui venoit frapper avec une extrême
vivacité le tenon du fil d'archal, & occasionnoit un bruit semblable
à celui qu'on feroit en frappant sur la tringle avec une clef. J'ai
répeté l'expérience au moins six fois dans l'espace d'environ quatre
minutes, en présence de plusieurs personnes, & chaque expérience
que j'ai faite a duré l'espace d'un pater & d'un_ ave. _J'ai voulu
continuer; l'action du feu s'est ralentie peu à peu; j'ai approché
plus près, & n'ai plus tiré que quelques étincelles, & enfin rien
n'ai paru._

_Le coup de tonnerre qui a occasionné cet événement, n'a été suivi
d'aucun autre; tout s'est terminé par une abondance de grêle. J'étois
si occupé dans le moment de l'expérience de ce que voyois, qu'ayant
été frappé au bras un peu au-dessus du coude, je ne puis dire si
c'est en touchant au fil d'archal ou à la tringle: je ne me suis pas
plaint du mal que m'avoit fait le coup dans le moment que je l'ai
reçu; mais comme la douleur continuoit, de retour chez moi, j'ai
découvert mon bras en présence de Coiffier, & nous avons apperçu une
meurtrissure tournante autour du brass, semblable à celle que feroit
un coup de fil d'archal, si j'en avois été frappé à nud. En revenant
de chez Coiffier, j'ai recontré M. le Vicaire, M. de Milly, et le
Maître d'école, à qui j'ai rapporté ce qui venoit d'arriver; ils se
sont plaints tous les trois qu'ils sentoient une odeur de soufre qui
les frappait davantage à mesure qu'ils s'approichient de moi: j'ai
porté chez moi la même odeur, & mes domestiques s'en sont apperçus
sans que je leur aye rien dit._

_Voilà, Monsieur, un récit fait à la hâte, mais naif & vrai que
j'atteste, & vous pouvez assurer que je suis prêt à rendre témoignage
de cet événement dans toutes les occasions. Coiffier a été le premier
qui a fait l'expérience & l'a répétée, plusieurs fois; ce n'est
qu'à l'occasion de ce qu'il a vu qu'il m'a envoyé prier de venir.
S'il étoit besoin d'autres témoins que de lui & de moi, vous les
trouveriez. Coiffier presse pour partir._

_Je suis avec une respectueuse considération, Monsieur, votre, &c.
signé_ RAULET, _Prieur de Marly. 10 Mai, 1752._

"On voit, par le détail de cette lettre, que le fait est assez bien
constaté pour ne laisser aucun doute à ce sujet. Le porteur m'a
assuré de vive voix qu'il avoit tiré pendant près d'un quart-d'heure
avant que M. le Prieur arrivât, en présence de cinq ou six
personnes, des étincelles plus fortes & plus bruyantes que celles
dont il est parlé dans la lettre. Ces premieres personnes arrivant
successivement, n'osient approcher qu'à 10 ou 12 pas de la machine; &
à cette distance, malgré le plein soleil, ils voyoient les étincelles
& entendoient le bruit....

"Il résulte de toutes les expériences & observations que j'ai
rapportées dans ce mémoire, & surtout de la dernière expérience faite
à Marly-la-ville, que la matiere du tonnerre est incontestablement la
même que celle de l'électricité. L'idée qu'en a eu M. Franklin cesse
d'être une conjecture: la voilà devenue une réalité, & j'ose croire
que plus on approfondira tout ce qu'il a publié sur l'électricité,
plus on reconnoîtra combien la physique lui est redevable pour cette
partie."

  _Letter of Mr. W. Watson, F. R. S. to the Royal Society, concerning
  the electrical Experiments in England upon Thunder-Clouds._

  Read Dec. 1752. Trans. Vol. XLVII.

  GENTLEMEN,

After the communications, which we have received from several of our
correspondents in different parts of the continent, acquainting us
with the success of their experiments last summer, in endeavouring to
extract the electricity from the atmosphere during a thunder-storm,
in consequence of Mr. Franklin's hypothesis, it may be thought
extraordinary, that no accounts have been yet laid before you, of our
success here from the same experiments. That no want of attention,
therefore, may be attributed to those here, who have been hitherto
conversant in these enquiries, I thought proper to apprise you, that,
though several members of the Royal Society, as well as myself, did,
upon the first advices from France, prepare and set up the necessary
apparatus for this purpose, we were defeated in our expectations,
from the uncommon coolness and dampness of the air here, during the
whole summer. We had only at London one thunder-storm; viz. on July
20; and then the thunder was accompanied with rain; so that, by
wetting the apparatus, the electricity was dissipated too soon to be
perceived upon touching those parts of the apparatus, which served
to conduct it. This, I say, in general prevented our verifying Mr.
Franklin's hypothesis: but our worthy brother, Mr. Canton, was more
fortunate. I take the liberty, therefore, of laying before you an
extract of a letter, which I received from that gentleman, dated from
Spital-square, July 21, 1752.

"I had yesterday, about five in the afternoon, an opportunity of
trying Mr. Franklin's experiment of extracting the electrical fire
from the clouds; and succeeded, by means of a tin tube, between three
and four feet in length, fixed to the top of a glass one, of about
eighteen inches. To the upper end of the tin tube, which was not
so high as a stack of chimnies on the same house, I fastened three
needles with some wire; and to the lower end was soldered a tin cover
to keep the rain from the glass tube, which was set upright in a
block of wood. I attended this apparatus as soon after the thunder
began as possible, but did not find it in the least electrified,
till between the third and fourth clap; when, applying my knuckle
to the edge of the cover, I felt and heard an electrical spark; and
approaching it a second time, I received the spark at the distance of
about half an inch, and saw it distinctly. This I repeated four or
five times in the space of a minute, but the sparks grew weaker and
weaker; and in less than two minutes the tin tube did not appear to
be electrified at all. The rain continued during the thunder, but was
considerably abated at the time of making the experiment." Thus far
Mr. Canton.

Mr. Wilson likewise of the Society, to whom we are much obliged for
the trouble he has taken in these pursuits, had an opportunity of
verifying Mr. Franklin's hypothesis. He informed me, by a letter from
near Chelmsford, in Essex, dated August 12, 1752, that, on that day
about noon, he perceived several electrical snaps, during, or rather
at the end of a thunder-storm, from no other apparatus than an iron
curtain rod, one end of which he put into the neck of a glass phial,
and held this phial in his hand. To the other end of the iron he
fastened three needles with some silk. This phial, supporting the
rod, he held in one hand, and drew snaps from the rod with a finger
of his other. This experiment was not made upon any eminence, but in
the garden of a gentleman, at whose house he then was.

Dr. Bevis observed, at Mr. Cave's, at St. John's Gate, nearly the
same phenomena as Mr. Canton, of which an account has been already
laid before the public.

Trifling as the effects here mentioned are, when compared with those
which we have received from Paris and Berlin, they are the only ones,
that the last summer here has produced; and as they were made by
persons worthy of credit, they tend to establish the authenticity of
those transmitted from our correspondents.

I flatter myself, that this short account of these matters will not
be disagreeable to you; and am,

  With the most profound respect,

  Your most obedient, humble servant,

  W. WATSON.

No. 2.

  _Remarks on the Abbé Nollet's Letters to Benjamin Franklin, Esq. of
  Philadelphia, on Electricity: by Mr. David Colden, of New York._

  _Coldenham, in New York, Dec. 4, 1753._

  SIR,

In considering the Abbé Nollet's Letters to Mr. Franklin, I am
obliged to pass by all the experiments which are made with, or in,
bottles hermetically sealed, or exhausted of air; because, not being
able to repeat the experiments, I could not second any thing which
occurs to me thereon, by experimental proof. Wherefore, the first
point wherein I can dare to give my opinion, is in the Abbé's 4th
letter, p. 66, where he undertakes to prove, that the electric matter
passes from one surface to another through the entire thickness
of the glass: he takes Mr. Franklin's experiment of the magical
picture, and writes thus of it. "When you electrise a pane of glass
coated on both sides with metal, it is evident that whatever is
placed on the side opposite to that which receives the electricity
from the conductor, receives also an evident electrical virtue."
Which Mr. Franklin says, is that equal quantity of electric matter,
driven out of this side, by what is received from the conductor on
the other side; and which will continue to give an electrical virtue
to any thing in contact with it, till it is entirely discharged of
its electrical fire. To which the Abbé thus objects; "Tell me (says
he), I pray you, how much time is necessary for this pretended
discharge? I can assure you, that after having maintained the
electrisation for hours, this surface, which ought, as it seems to
me, to be entirely discharged of its electrical matter, considering
either the vast number of sparks that were drawn from it, or the time
that this matter had been exposed to the action of the expulsive
cause; this surface, I say, appeared rather better electrised
thereby, and more proper to produce all the effects of an actual
electric body." _P._ 68.

The Abbé does not tell us what those effects were, all the effects
I could never observe, and those that are to be observed can easily
be accounted for, by supposing that side to be entirely destitute
of electric matter. The most sensible effect of a body charged with
electricity is, that when you present your finger to it, a spark will
issue from it to your finger: now when a phial, prepared for the
Leyden experiment, is hung to the gun-barrel or prime-conductor, and
you turn the globe in order to charge it; as soon as the electric
matter is excited, you can observe a spark to issue from the external
surface of the phial to your finger, which, Mr. Franklin says, is
the natural electric matter of the glass driven out by that received
by the inner surface from the conductor. If it be only drawn out by
sparks, a vast number of them may be drawn; but if you take hold of
the external surface with your hand, the phial will soon receive all
the electric matter it is capable of, and the outside will then be
entirely destitute of its electric matter, and no spark can be drawn
from it by the finger: here then is a want of that effect which all
bodies, charged with electricity, have. Some of the effects of an
electric body, which I suppose the Abbé has observed in the exterior
surface of a charged phial, are that all light bodies are attracted
by it. This is an effect which I have constantly observed, but do not
think that it proceeds from an attractive quality in the exterior
surface of the phial, but in those light bodies themselves, which
seem to be attracted by the phial. It is a constant observation,
that when one body has a greater charge of electric matter in it
than another (that is in proportion to the quantity they will hold)
this body will attract that which has less: now, I suppose, and it
is a part of Mr. Franklin's system, that all those light bodies
which appear to be attracted, have more electric matter in them than
the external surface of the phial has, wherefore they endeavour to
attract the phial to them, which is too heavy to be moved by the
small degree of force they exert, and yet being greater than their
own weight, moves them to the phial. The following experiment will
help the imagination in conceiving this. Suspend a cork ball, or a
feather, by a silk thread, and electrise it; then bring this ball
nigh to any fixed body, and it will appear to be attracted by that
body, for it will fly to it: now, by the consent of electricians, the
attractive cause is in the ball itself, and not in the fixed body to
which it flies: this is a similar case with the apparent attraction
of light bodies, to the external surface of a charged phial.

The Abbé says, _p._ 69, "that he can electrise a hundred men,
standing on wax, if they hold hands, and if one of them touch one
of these surfaces (the exterior) with the end of his finger:" this
I know he can, while the phial is charging, but after the phial is
charged I am as certain he cannot: that is, hang a phial, prepared
for the Leyden experiment, to the conductor, and let a man, standing
on the floor, touch the coating with his finger, while the globe is
turned, till the electric matter spews out of the hook of the phial,
or some part of the conductor, which I take to be the certainest sign
that the phial has received all the electric matter it can: after
this appears, let the man, who before stood on the floor, step on a
cake of wax, where he may stand for hours, and the globe all that
time turned; and yet have no appearance of being electrised. After
the electric matter was spewed out as above from the hook of the
phial prepared for the Leyden experiment, I hung another phial, in
like manner prepared, to a hook fixed in the coating of the first,
and held this other phial in my hand; now if there was any electric
matter transmitted through the glass of the first phial, the second
one would certainly receive and collect it; but having kept the
phials in this situation for a considerable time, during which the
globe was continually turned, I could not perceive that the second
phial was in the least charged, for when I touched the hook with
my finger, as in the Leyden experiment, I did not feel the least
commotion, nor perceive any spark to issue from the hook.

I likewise made the following experiment: having charged two phials
(prepared for the Leyden experiment) through their hooks; two persons
took each one of these phials in their hand; one held his phial by
the coating, the other by the hook, which he could do by removing
the communication from the bottom before he took hold of the hook.
These persons placed themselves one on each side of me, while I stood
on a cake of wax, and took hold of the hook of that phial which was
held by its coating (upon which a spark issued, but the phial was not
discharged, as I stood on wax) keeping hold of the hook, I touched
the coating of the phial that was held by its hook with my other
hand, upon which there was a large spark to be seen between my finger
and the coating, and both phials were instantly discharged. If the
Abbé's opinion be right, that the exterior surface, communicating
with the coating, is charged, as well as the interior, communicating
with the hook; how can I, who stand on wax, discharge both these
phials, when it is well known I could not discharge one of them
singly? Nay, suppose I have drawn the electric matter from both of
them, what becomes of it? For I appear to have no additional quantity
in me when the experiment is over, and I have not stirred off the
wax: wherefore this experiment fully convinces me, that the exterior
surface is not charged; and not only so, but that it wants as much
electric matter as the inner has of excess: for by this supposition,
which is a part of Mr. Franklin's system, the above experiment is
easily accounted for, as follows:

When I stand on wax, my body is not capable of receiving all the
electric matter from the hook of one phial, which it is ready to
give; neither can it give as much to the coating of the other phial
as it is ready to take, when one is only applied to me: but when both
are applied, the coating takes from me what the hook gives: thus I
receive the fire from the first phial at B, the exterior surface of
which is supplied from the hand at A: I give the fire to the second
phial at C, whose interior surface is discharged by the hand at D.
This discharge at D may be made evident by receiving that fire into
the hook of a third phial, which is done thus: In place of taking
the hook of the second phial in your hand, run the wire of a third
phial, prepared as for the Leyden experiment, through it, and hold
this third phial in your hand, the second one hanging to it, by
the ends of the hooks run through each other: when the experiment
is performed, this third phial receives the fire at D, and will be
charged.

[Illustration: (of the experiment above)]

When this experiment is considered, I think, it must fully prove
that the exterior surface of a charged phial wants electric matter,
while the inner surface has an excess of it. One thing more worthy
of notice in this experiment is, that I feel no commotion or shock in
my arms, though so great a quantity of electric matter passes them
instantaneously: I only feel a pricking in the ends of my fingers.
This makes me think the Abbé has mistook, when he says, that there
is no difference between the shock felt in performing the Leyden
experiment, and the pricking felt on drawing simple sparks, except
that of greater to less. In the last experiment, as much electric
matter went through my arms, as would have given me a very sensible
shock, had there been an immediate communication, by my arms, from
the hook to the coating of the same phial; because when it was taken
into a third phial, and that phial discharged singly through my arms,
it gave me a sensible shock. If these experiments prove that the
electric matter does not pass through the entire thickness of the
glass, it is a necessary consequence that it must always come out
where it entered.

The next thing I meet with is in the Abbé's fifth letter, _p._
88, where he differs from Mr. Franklin, who thinks that the whole
power of giving a shock is in the glass itself, and not in the
non-electrics in contact with it. The experiments which Mr. Franklin
gave to prove this opinion, in his _Observations on the Leyden
Bottle_, p. 179, convinced me that he was in the right; and what the
Abbé has asserted, in contradiction thereto, has not made me think
otherwise. The Abbé, perceiving, as I suppose, that the experiments,
as Mr. Franklin had performed them, must prove his assertion, alters
them without giving any reason for it, and makes them in a manner
that proves nothing. Why will he have the phial, into which the,
water is to be decanted from a charged phial, held in a man's hand?
If the power of giving a shock is in the water contained in the
phial, it should remain there though decanted into another phial,
since no non-electric body touched it to take that power off. The
phial being placed on wax is no objection, for it cannot take the
power from the water, if it had any, but it is a necessary means to
try the fact; whereas, that phial's being charged when held in a
man's hand, only proves that water will conduct the electric matter.
The Abbé owns, _p._ 94, that he had heard this remarked, but says,
Why is not a conductor of electricity an electric subject? This is
not the question; Mr. Franklin never said that water was not an
electric subject; he said, that the power of giving a shock was in
the glass, and not in the water; and this, his experiments fully
prove; so fully, that it may appear impertinent to offer any more:
yet as I do not know that the following has been taken notice of by
any body before, my inserting of it in this place may be excused.
It is this: Hang a phial, prepared for the Leyden experiment, to
the conductor, by its hook, and charge it, which done, remove the
communication from the bottom of the phial. Now the conductor shews
evident signs of being electrised; for if a thread be tied round it,
and its ends left about two inches long, they will extend themselves
out like a pair of horns; but if you touch the conductor, a spark
will issue from it, and the threads will fall, nor does the conductor
shew the least sign of being electrised after this is done. I think
that by this touch, I have taken out all the charge of electric
matter that was in the conductor, the hook of the phial, and water
or filings of iron contained in it; which is no more than we see all
non-electric bodies will receive: yet the glass of the phial retains
its power of giving a shock, as any one will find that pleases to
try. This experiment fully evidences, that the water in the phial
contains no more electric matter than it would do in an open bason,
and has not any of that great quantity which produces the shock, and
is only retained by the glass. If after the spark is drawn from the
conductor, you touch the coating of the phial (which all this while
is supposed to hang in the air, free from any non-electric body)
the threads on the conductor will instantly start up, and shew that
the conductor is electrised. It receives this electrisation from
the inner surface of the phial, which, when the outer surface can
receive what it wants from the hand applied to it, will give as much
as the bodies in contact with it can receive, or if they be large
enough, all that it has of excess. It is diverting to see how the
threads will rise and fall by touching the coating and conductor of
the phial alternately. May it not be that the difference between
the charged side of the glass, and the outer or emptied side, being
lessened by touching the hook or the conductor; the outer side can
receive from the hand which touched it, and by its receiving, the
inner side cannot retain so much; and for that reason so much as it
cannot contain electrises the water, or filings and conductor: for
it seems to be a rule, that the one side must be emptied in the same
proportion that the other is filled: though this from experiment
appears evident, yet it is still a mystery not to be accounted for.

I am in many places of the Abbé's book surprised to find that
experiments have succeeded so differently at Paris, from what they
did with Mr. Franklin, and as I have always observed them to do. The
Abbé, in making experiments to find the difference between the two
surfaces of a charged glass, will not have the phial placed on wax:
for, says he, don't you know that being placed on a body originally
electric, it quickly loses its virtue? I cannot imagine what should
have made the Abbé think so; it certainly is contradictory to the
notions commonly received of electrics _per se_; and by experiment I
find it entirely otherwise: for having several times left a charged
phial, for that purpose, standing on wax for hours, I found it to
retain as much of its charge as another that stood at the same time
on a table. I left one standing on wax from ten o'clock at night
till eight the next morning, when I found it to retain a sufficient
quantity of its charge, to give me a sensible commotion in my arms,
though the room in which the phial stood had been swept in that time,
which must have raised much dust to facilitate the discharge of the
phial.

I find that a cork-ball suspended between two bottles, the one fully
and the other but little charged, will not play between them, but is
driven into a situation that makes a triangle with the hooks of the
phials: though the Abbé has asserted the contrary of this, p. 101,
in order to account for the playing of a cork-ball between the wire
thrust into the phial, and one that rises up from its coating. The
phial which is least charged must have more electric matter given to
it, in proportion to its bulk, than the cork-ball receives from the
hook of the full phial.

The Abbé says, p. 103, "That a piece of metal leaf hung to a silk
thread and electrised, will be repelled by the bottom of a charged
phial held by its hook in the air:" this I find constantly otherwise,
it is with me always first attracted and then repelled: it is
necessary in charging the leaf to be careful, that it does not fly
off to some non-electric body, and so discharge itself when you think
it is charged; it is difficult to keep it from flying to your own
wrist, or to some part of your body.

The Abbé, p. 108, says, "that it is not impossible, as Mr. Franklin
says it is, to charge a phial while there is a communication formed
between its coating and its hook." I have always found it impossible
to charge such a phial so as to give a shock: indeed, if it hang on
the conductor without a communication from it, you may draw a spark
from it as you may from any body that hangs there, but this is very
different from being charged in such a manner as to give a shock. The
Abbé, in order to account for the little quantity of electric matter
that is to be found in the phial, says, "that it rather follows the
metal than the glass, and that it is spewed out into the air from
the coating of the phial." I wonder how it comes not to do so too,
when it sifts through the glass, and charges the exterior surface,
according to the Abbé's system!

The Abbé's objections against Mr. Franklin's two last experiments, I
think, have little weight in them: he seems, indeed, much at a loss
what to say, wherefore he taxes Mr. Franklin with having concealed a
material part of the experiment; a thing too mean for any gentleman
to be charged with, who has not shown as great a partiality in
relating experiments, as the Abbé has done.

  END OF VOLUME THE FIRST.

  J. CUNDEE, PRINTER,

  IVY-LANE.

  INDEX.

  A.

  _Accent_, or emphasis, wrong placing of, a fault in modern tunes, ii. 345.

  _Accidents_ at sea, how to guard against, ii. 172.

  _Adams_, Mr. Matthew, offers the use of his library to Franklin, i. 16.

  _Addison_, Franklin an assiduous imitator of, in his youth, i. 13.

  _Advice_ to youth in reading, ii. 378.
      to emigrants to America, iii. 398.
      to a crafty statesman, 430.
      to a young tradesman, 463.
      to a young married man, 477.
      to players at chess, 490.

  _Æpinus_, his hypothesis of magnetism, i. 412.

  _Agriculture_ takes place of manufactures till a country is fully settled,
               iii. 107.
      the great business of America, 393.

  _Air_, some of the properties of, ii. 226.
      its properties with respect to electricity, i. 204.
      properties of its particles, 205. ii. 1.
      its currents over the globe, i. 207.
      resists the electric fluid and confines it to bodies, 241.
      its effects in electrical experiments, 253.
      its elasticity not affected by electricity, 254.
      its friction against trees, 270, 323.
      has its share of electricity, 333.
      its electricity denser above than below, 335.
      in rooms, electrified positively and negatively, 353.
      attracts water, ii. 1.
      when saturated with water precipitates it, 2.
      dissolves water, and, when dry, oil, 4.
      why suffocating, when impregnated with oil or grease, _ibid._
      supports water, 5, 46, 49.
      why less heated in the higher regions than near the earth's surface,
               6.
      how it creates hurricanes, _ibid._
          winds, 8.
          whirlwinds, 10.
      effects of heat upon, 50.
      its effects on the barometer, 92.
      condensed, supposed to form the centre of the earth, 119, 127.
      noxious, corrected by vegetation, 129.
      observations on the free use of, 213.
      rare, no bad conductor of sound, 337.
      fresh, beneficial effects of, in bed-rooms, iii. 495.

  _Air-thermometer_, electrical, experiments with, i. 336.

  _Albany_ plan of union, short account of, i. 127.
      its singular fate, 129.
      papers relating to, iii. 3.
      motives on which formed, 4.
      rejects partial unions, 6.
      its president and grand council, 9.
      election of members, 12.
      place of first meeting, 13.
      new election, _ibid._
      proportion of members after three years, 15.
      meetings of the grand council and call, 16.
      allowance to members, 17.
      power of president and his duty, 18.
      treaties of peace and war, _ibid._
      Indian trade and purchases, 19.
      new settlements, 21.
      military establishments, 23.
      laws and taxes, 24, 26.
      issuing of money, 25.
      appointment of officers, 27.
      rejected in England, 29.

  _Almanack._ _See Poor Richard._

  _Alphabet_, a new one proposed, ii. 357.
      examples of writing in it, 360.
      correspondence on its merits, 361.

  _Amber_, electrical experiments on, i. 403.

  _America_, North, air of, drier than that of England and France, ii. 140.
      why marriages are more frequent there than in Europe, 385.
      why labour will long continue dear there, _ibid._
      argument against the union of the colonies of, under one government,
               401.
      state of toleration there, 457.
      reflections on the scheme of imposing taxes on, without its consent,
               iii. 30.
      thoughts on the representation of, in the British parliament, 37.
      interest of Great Britain with regard to, 39.
      forts in the back settlements of, no security against France, 99.
      wars carried on there against the French, not merely in the cause of
               the colonies, 105.
      preference of the colonies of, to the West Indian colonies, 113.
      great navigable rivers of, favourable to inland trade, 118.
      what commodities the inland parts of, are fitted to produce, 119.
      the productions of, do not interfere with those of Britain, 123.
      union of the colonies of, in a revolt against Britain, impossible but
               from grievous oppression, 132.
      reasons given for restraining paper-bills of credit there, 144.
      intended scheme of a bank there, described, 155.
      attempts of Franklin for conciliation of Britain with, 286.
      feeling of, as to Britain, in May 1775, 346.
      conciliation of Britain with, hopeless, 355.
      account of the first campaign of the British forces against, 357.
      application of, to foreign courts, for aid in its independence, 360.
      credit of, with that of Britain, in 1777, compared, 372.
      true description of the interest and policy of, 391.
      information to those emigrating thither, 398.
      terms on which land may be obtained for new settlements there, 409.

  _Americans_, their prejudices for whatever is English, i. 144.

  _Anchor_, a swimming one proposed, ii. 181, 185.

  _Ancients_, their experimental learning too often slighted, ii. 146.

  _Anecdote_ of Franklin's early spirit of enterprise, i. 11.
      of a Swedish clergyman among the Indians, iii. 386.
      of an Indian who went to church, 389.

  _Animal_ food, Franklin's abstinence from, i. 20.
      return to, 47.
      humorous instance of abstinence from, 49.
      heat, whence it arises, ii. 79, 125.
      magnetism, detected and exposed, i. 150.

  _Animalcules_, supposed to cause the luminous appearance of sea-water,
               ii. 89.

  _Animals_, how to kill them by electricity, i. 415.

  _Antifederalists_ of America, comparison of, to the ancient Jews,
               iii. 410.

  _Apprentices_ easier placed out in America than in Europe, iii. 407.
      indentures of, how made in America, 408.

  _Argumentation_, bad effects of, as a habit, i. 17.
      best method of, 22.

  _Armies_, best means of supporting them, ii. 400.

  _Armonica_, musical instrument so called, described, ii. 330.
      manner of playing on it, 334.

  _Asbestos_, specimen of, sold by Franklin to Sir Hans Sloane, i. 60.
      letter relating to it, iii. 513.

  _Astrology_, letter to the Busy-body on, iii. 448.

  _Atmosphere_ sometimes denser above than below, ii. 6.
      electrical, its properties, i. 294.

  _Aurora borealis_ explained, i. 212.
      conjectures respecting, 257, ii. 69.
      query concerning, i. 293.

  B.

  _Badoin_, Mr. letters from, i. 314, 324.

  _Ballads_, two, written by Franklin in his youth, i. 16.

  _Balls_ of fire in the air, remark concerning, ii. 337.

  _Barometer_, how acted on by air, ii. 92.

  _Barrels_ for gunpowder, new sort proposed, i. 376.

  _Bass_, unnecessary in some tunes, ii. 343.

  _Bathing_ relieves thirst, ii. 104.
      observations on, 211.

  _Battery_, electrical, its construction, i. 193.

  _Baxter_, Mr. observations on his enquiry into the nature of the soul,
               ii. 110.

  _Beccaria_, character of his book on electricity, i. 310.

  _Beer_, not conducive to bodily strength, i. 62.

  _Bells_, form in consecrating them at Paris, i. 384.

  _Belly-ache_, dry, lead a cause of, ii. 220.

  _Bermuda_, little thunder there, i. 216.

  _Bermudian_ sloops, advantages of their construction, ii. 173.

  _Bernoulli_, Mr. his plan for moving boats, ii. 179.

  _Bevis_, Dr. draws electricity from the clouds, i. 429.

  _Bible_, anecdote of its concealment in the reign of Mary, i. 7.
      travestied by Dr. Brown, 31.

  _Bills_ of mortality, reasonings, formed on those for capital cities,
               not applicable to the country, ii. 383.

  _Birth_, noble, no qualification in America, iii. 400.

  _Bishops_, none in America, and why, ii. 456, 458.

  _Black clothes_ heat more and dry sooner than white, ii. 108.
      not fit for hot climates, 109.

  _Blacksmith_, trade of, hereditary in Franklin's family, i. 4.

  _Blindness_ occasioned both by lightning and electricity, i. 228.

  _Boats_, difference of their sailing in shoal and deep water, ii. 160.
      management of, best understood by savages, 176.
      how rowed by the Chinese, 177.
      methods of moving them by machinery, _ibid._
      improvement of Mr. Bernoulli's plan for moving them, 179.
      proposal for a new mode of moving them, _ibid._
      double, advantage of, 173, 174.
      one built by Sir W. Petty, _ibid._

  _Bodies_, electrified negatively, repel each other, ii. 294.
      effect of blunt, compared with pointed ones, i. 172, 223.

  _Body_, human, specifically lighter than water, ii. 208.
      political and human, compared, iii. 115.

  _Boerhaave_, his opinion of the propagation of heat, ii. 58.
      of steam from fermenting liquors, 59.

  _Boiling_ water, experiments with, i. 332, 344, 345.
      pot, bottom of, why cold, 387.

  _Bolton_, Mr. experiment by, i. 346.

  _Books_ read by Franklin in his youth, i. 15, 18, 20, 21.

  _Boston_, the birth-place of Franklin, i. 8.
      why quitted by him in his youth, 27,
      its inhabitants decrease, ii. 210.
      preface to proceedings of the town meeting of, iii. 317.

  _Boyle's_ lectures, effect of, on Franklin, i. 79.

  _Braddock_, general, defeat of, i. 131.

  _Bradford_, printer at Philadelphia, i. 34, 102.

  _Brass_, hot, yields unwholesome steams, ii. 249

  _Brientnal_, Joseph, a member of the Junto club, i. 83.

  _Brimstone_, when fluid, will conduct electricity, i. 256.

  _Bristol waters_, an alledged fact concerning, ii. 95.

  _Britain_, incapacity of, to supply the colonies with manufactures,
               ii. 386.

  _British empire_, an union of several states, iii. 310.

  _Brown_, Dr. acquaintance of Franklin's, i. 30.
      travestied the bible, 31.

  _Bubbles_ on the surface of water, hypothesis respecting, ii. 48.

  _Buchan_, earl of, letter to, on the price of land for new settlements
               in America, iii. 409.

  _Buildings_, what kind safest from lightning, i. 379.

  _Bullion_, causes of its variation in price, iii. 153.

  _Bunyan's_ Voyages, a book early read by Franklin, i. 15, 28.

  _Bur_, cause of, round a hole struck through pasteboard, i. 280.

  _Burnet_, governor, his attention to Franklin in his youth, i. 44.

  _Busy-body_, essays under the title of, i. 86. iii. 422.

  C.

  _Cabinet-work_, veneered in England, shrinks and flies in America,
               ii. 140.

  _Cables_, why apt to part when weighing anchor in a swell, ii. 167.
      this defect of, remedied, 168.

  _Cabot_, Sebastian, his commission from Henry VII., iii. 348.

  _Calvinism_, Franklin educated in the principles of, i. 79.

  _Campaign_ in America, account of the first, iii. 357.

  _Canals_, observations on their depth, ii. 159.

  _Canada_, importance of, to England, i. 136.
      visited by Franklin, 147.
      its extent, iii. 20.
      pamphlet on the importance of, 89.
      easily peopled without draining Britain, 139.

  _Cancers_, specific for, i. 260, 261.

  _Candles_ lighted by electricity, i. 176.
      distance at which the flame of, may be seen, ii. 90.

  _Cann_, silver, a singular experiment on, i. 307.

  _Canoes_ of the American Indians, their advantages, ii. 176.

  _Canton_, Mr. John, experiments by, i. 286, 346.
      draws electricity from the clouds, 428.

  _Capitals_, their use in printing, ii. 352.

  _Caribbees_, possession of, only a temporary benefit, iii. 142.

  _Carolina_, South, see _Lightning_.

  _Cavendish_, lord Charles, his electrical experiments, i. 348.

  _Cayenne_ would be a great acquisition to Britain, iii. 140.

  _Centre_ of the earth, hypothesis concerning, ii. 119, 127.

  _Cessions_ from an enemy, on what grounds may be demanded, iii. 93.

  _Chapel_, nickname for a printing house, i. 63.

  _Character_, remarks on the delineation of, iii. 445.

  _Charcoal-fires_, hurtful, ii. 235.

  _Charging_ and discharging, in electricity, explained, i. 190.
      a number of bottles at once, how done, _ibid._

  _Charters_ of the colonies could not be altered by parliament, iii. 332.

  _Chess_, morals of, iii. 488.
      not an idle amusement, _ibid._
      teaches various virtues, 489.
      advice to those who play, 490.
      too intense an application to, injurious, 500.

  _Chimnies_, different kinds of, enumerated, ii. 228.
      inconvenience of the old-fashioned ones, 229.
      defect of more modern ones, 230.
      have not long been in use in England, 277.
      Staffordshire, described, 285.
      have a draft of air up and down, 289.
      may be used for keeping provisions in summer, 290.
      may be of use to miners, 291.
      funnels to, what the best, 292, 295.
      method of contracting them, 317.
      smoky. See _Smoky_.

  _China_, provision made there against famine, ii. 407.

  _Chinese_ wisely divide the holds of their vessels by partitions, ii. 171.
      how they row their boats, 177.
      their method of warming ground floors, 292.
      improvement in this method suggested, 293.
      their method of making large paper, 349.

  _Circle_, magical, account of, ii. 327, 328.

  _Cities_, spring water gradually deteriorates in, i. 163.
      do not supply themselves with inhabitants, ii. 384.

  _Clark_, Dr. of Boston, quoted, on the instigation of the American
               Indians against the English, iii. 95, 100, 102.

  _Clothes_, wet, may preserve from lightning, i. 213.
          will relieve thirst, ii. 104.
          do not give colds, _ibid._
      imbibe heat according to their colour, 108.
      white, most suitable for hot climates, _ibid._

  _Clothing_ does not give, but preserves, warmth, ii. 81.

  _Clouds_, at land and at sea, difference between, i. 207.
      formed at sea, how brought to rain on land, 208.
          driven against mountains, form springs and rivers, 209.
      passing different ways, accounted for, 211.
      electrical, attracted by trees, spires, &c. 213.
      manner in which they become electrised, 257, 305.
      are electrised sometimes negatively and sometimes positively, 274,
               277, 284, 292.
      electricity drawn from them, at Marly, 420.
          by Mr. Cauton, 428.
          by Dr. Bevis, 429,
          by Mr. Wilson, _ibid._
      how supported in air, ii. 5.
      how formed, 7.
      whether winds are generated or can be confined in them, 57.
      have little more solidity than fogs, _ibid._

  _Club_, called the Junto, instituted by Franklin, i. 82.
      rules of, ii. 366, 369.
      questions discussed in, 369.

  _Coal_, sea, letter on the nature of, ii. 128.

  _Cold_, why seemingly greater in metals than in wood, ii. 56, 77.
      sensation of, how produced, 57.
      only the absence of heat, 81.
      produced by chemical mixtures, _ibid._
          evaporation. See _Evaporation_.

  _Colden_, Mr. his remarks on Abbé Nollet's letters, i. 430.
      meteorological observations, ii. 51.
      observations on water-spouts, 53.

  _Colds_, causes of, ii. 214, 230.

  _Coleman_, William, a member of the Junto club, i. 84, 89.

  _Colica pictorum_, caused by lead, ii. 219.

  _Collins_, John, an early friend of Franklin's, i. 17, 27, 41, 43, 44.

  _Collinson_, Mr. some account of, iii. 514.

  _Colonial_ governments in America of three kinds, iii. 50.

  _Colonies_, the settlement of, does not diminish national numbers,
               ii. 391.
      their prosperity beneficial to the mother country, iii. 113.
      are intitled to distinct governments, 303.
      American, preferable to the West Indies, _ibid._
          not dangerous to Britain, 132.
          aids to government, how given by, 225, 226.
          originally governed by the crown, independent of Parliament,
               291.
          not settled at the expence of Britain, 348.

  _Colonists_ in America, double their number in 25 years, iii. 113.
      from Britain, their rights, 299.

  _Colours._ See _Clothes_.

  _Comazants_, or corposants, are electrical appearances, i. 248.

  _Commerce_, influence of, on the manners of a people, ii. 400.
      is best encouraged by being left free, 415.
      should not be prohibited in time of war, 417.
      by inland carriage, how supported, iii. 116.

  _Common-sense_, by Paine, Franklin supposed to have contributed to,
               i. 148.

  _Compass_, instances of its losing its virtue by lightning, i. 248.
      how to remedy the want of, at sea, ii. 191.

  _Conductors_ of lightning, very common in America, i. 113.
          first suggestion of the utility of, 227.
          construction of, 358.
          particulars relating to, 377.
      of electricity, difference in the action of, 200, 303.
          which the most perfect, 253, 256.
      and non-conductors, other terms substituted for, _ibid._
      of common fire, their properties and differences, ii. 76, 77.
          experiments on, ii. 77.

  _Congress_, Franklin appointed a delegate to, i. 146.
      proposed overture from, in 1775, iii. 347.

  _Consecration_ of bells in France, form of, i. 384.

  _Conspirators_, electrical, meaning of the term, i. 196.

  _Controversy_, benefit of, iii. 92.

  _Conversation_, advantage of useful topics of, at dinner, i. 12.

  _Cook_, captain, circular letter concerning, iii. 515.
      copy of the voyages of, presented to Franklin, by the Admiralty, 517.

  Cookery, at sea, generally bad, ii. 194.

  _Copper_, manner of covering houses with, ii. 318, 320, 322.

  _Copper_ plate printing-press, the first in America, constructed by
               Franklin, i. 77.

  _Corn_, ill policy of laying restraints on the exportation of, ii. 413,
               418.

  _Countries_, distant and unprovided, a plan for benefiting, ii. 403.

  _Creation_, conjectures as to, ii. 118.

  _Credit_, that of America and Britain in 1777, compared, iii. 372.
      depends on payment of loans, 373.
         industry and frugality, 374.
         public spirit, 375.
         income and security, 376.
         prospects of future ability, _ibid._
         prudence, 377.
         character for honesty, 378.
      is money to a tradesman, 464.

  _Criminal_ laws, reflections on, ii. 439.

  _Crooked_ direction of lightning explained, i. 316.

  _Cutler_, circumstance that prevented Franklin's being apprenticed to
               one, i. 14.

  _Currents_ at sea, often not perceivable, ii. 185.

  _Cyder_, the best quencher of thirst, ii. 195.

  D.

  _Dalrymple_, Mr. scheme of a voyage under his command to benefit remote
               regions, ii. 403.

  _Damp_ air, why more chilling than dry air that is colder, ii. 56, 77.

  _Dampier_, account of a water-spout by, ii. 33.
      references to his voyage, on the subject of water-spouts, 58.

  _Dampness_ on walls, cause of, ii. 50.

  _Day-light_, proposal to use it instead of candle-light, iii. 470.

  _Deacon_, Isaac, from an underling to a surveyor, becomes inspector-
              general of America, i. 78.
      prognosticates the future eminence in life of Franklin, _ib._

  _Death_ of Franklin, i. 153.
          letter from Dr. Price on, iii. 541.
      of relatives, reflections on, 507.

  _Deism_, effects on Franklin of books written against, i. 79.

  _Deluge_, accounted for, ii. 127.

  _Denham_, a quaker, a friend of Franklin's, i. 54.
      extraordinary trait of honesty of, to his creditors, 67.
      Franklin's engagement with, as a clerk, 68, 70.

  _Denmark_, the people of, not subject to colds, ii. 244.

  _Denny_, governor, remarks on his official conduct in Pensylvania,
               iii. 170.

  _Desaquiliers_, his experiment on the vapour of hot iron, ii. 249.

  _Dew_, how produced, i. 207.

  _Dialogue_, between Franklin and the gout, iii. 499.

  _Dickenson_, Mr. his remarks on the views of England in framing laws
               over the colonies, iii. 234.
      remarks on his conduct, 192.
          on his protest, 202.

  _Discontented_ dispositions satirized, iii. 485.

  _Discontents_ in America before 1768, causes of, iii. 225.

  _Dissentions_ between England and America, letter on, iii. 310.

  _Dissertation_, early one of Franklin's, that he repented having written,
               i. 58.

  _Disputation_, modesty in, recommended, i. 21. ii. 317.

  _Disputes_ between Franklin and his brother, to whom he was apprenticed,
               i. 24.

  _Domien_, a traveller, short account of, i. 302.

  _Drawling_, a defect in modern tunes, ii. 345.

  _Dreams_, art of procuring pleasant ones, iii. 493.

  _Dumas_, Monsieur, letter to, on the aid wanted by America in her struggle
               for independence, iii. 360.

  _Duna_ river, not to be confounded with the Dwina, iii. 119, note.

  _Dust_, how raised and carried up into the air, ii. 3.

  _Duties_, moral, the knowledge of, more important than the knowledge of
               nature, ii. 95.

  _Dutch_ iron stove, advantages and defects of, ii. 233.

  E.

  _Early_ impressions, lasting effect of, on the mind, iii. 478.

  _Earth_ will dissolve in air, ii. 2.
      dry, will not conduct electricity, i. 206.
      the, sometimes strikes lightning into the clouds, 274.
          grows no hotter under the summer sun, why, ii. 86.
          different strata of, 116.
          theory of, 117.

  _Earthquakes_, general good arising from, ii. 116.
      how occasioned, 120, 128.

  _Eaton_, in Northamptonshire, residence of Franklin's family, i. 3.

  _Ebb_ and flood, explanation of the terms, ii. 100.

  _Economical_ project, iii. 469.

  _Edinburgh_, an ordinance there against the purchase of prize-goods,
               ii. 447.

  _Education_ of women, controversy respecting, i. 17.

  _Eel_, electrical, of Surinam, i. 408, 409.

  _Effluvia_ of drugs, &c. will not pass through glass, i. 243.

  _Electrical_ air-thermometer described, i. 336, _et seq._
      atmosphere, how produced, 221.
          how drawn off, 222.
      atmospheres repel each other, 294.
          repel electric matter in other bodies, _ib._
      battery, its construction, 193.
      clouds, experiment regarding, 229.
      death, the easiest, 307.
      experiments, Franklin's eager pursuit of, 104.
          made in France, 109.
          various, 182, 229, 254, 255, 261, 271, 278, 286, 294, 307, 327,
               337, 348, 371, 434.
      fire, not created by friction, but collected, 173.
          passes through water, 202.
          loves water and subsists in it, 203.
          diffused through all matter, 205
          visible on the surface of the sea, _ibid._
          its properties and uses, 214, _et seq._
          produces common fire, 214, 238, 356.
          has the same crooked direction as lightning, 315.
      fluid, its beneficial uses, 219.
          is strongly attracted by glass, 236.
          manner of its acting through glass hermetically sealed, 241.
          a certain quantity of, in all kinds of matter, 275.
          nature of its explosion, 280.
          chooses the best conductor, 281, 378.
      force, may be unboundedly increased, 251.
      horse-race, 334.
      jack for roasting, 197.
      kiss, its force increased, 177.
      kite, described, 268.
      machine; simple and portable one, described, 178.
      matter, its properties, 217, 294.
      party of pleasure, 202.
      phial, or Leyden bottle, its phenomena explained, 179.
      shock, observations on, 182.
          effects of a strong one on the human body, 297, 306.
      spark, perforates a quire of paper, 195.
      wheel, its construction, 196.
          self-moving one, 198.

  _Electricity_, summary of its progress, i. 104.
      positive and negative, discovered, 106.
          distinguished, 175.
          in a tourmalin, 370.
      does not affect the elasticity of the air, 254.
      its similarity to lightning, 288.
      its effects on paralysis, 401.
      of fogs in Ireland, 405.
      supposed affinity between, and magnetism, 410.

  _Electrics per se_ and non-electrics, difference between, i. 242, 258.

  _Electrified_ bumpers described, i. 203.

  _Electrisation_, what constitutes the state of, i. 218.
      various appearances of, 175.
      variety of, 176.

  _Electrising_ one's self, manner of, i. 174.

  _Elocution_, how best taught, ii. 374.

  _Embassador_ from the United States to France, Franklin appointed to the
               office of, i. 148.

  _Emblematical_ design illustrative of the American troubles, iii. 371.

  _Emigrants_ to America, advice to, iii. 398.

  _Empire_, rules for reducing a great one, iii. 334.

  _England_, Franklin's first arrival in, i. 55.
          second arrival in, as agent for the province of Pensylvania, 134.
          third arrival in, as agent for the same province, 141.
      its air moister than that of America, ii. 140.
      decrease of population in, doubtful, 296.

  _English_, effect of the ancient manners of, ii. 399.
      language, innovations in, 351.

  _Enterprises_, public, Franklin's early disposition for, i. 10.

  _Ephemera_, an emblem of human life, iii. 508.

  _Epitaph_ on Franklin's parents, i. 13.
      on himself, 155.

  _Episcopalians_, conduct of the American legislature towards, ii. 455.

  _Errors_ of Franklin's early life, i. 45, 58, 61, 80, 97.

  _Ether_, what, ii. 59.

  _Evaporation_, cold produced by, i. 344, ii. 76, 83, 85.
      of rivers, effects of, 106.

  _Examination_ of Franklin before the house of commons, i. 142, iii. 245.
      before the privy council, 328.
      further particulars of, 551.

  _Exchange_, rate of, between Philadelphia and Britain, iii. 252.

  _Exercise_, should precede meals, iii. 493.

  _Experiments_, to show the electrical effect of points, i. 171, 172.
      to prove the electrical state of the Leyden phial, 182.
      of firing spirits by a spark sent through a river, 202.
      to show how thunder-storms produce rain, 209.
      on the clouds, proposed, 228.
      on drugs electrified, 243.
      on the elasticity of the air, 254.
      on the electric fluid, 255.
      by Mr. Kennersley, 261.
      on the electricity of the clouds, 271.
      for increasing electricity, 278.
      by Mr. Canton, 286.
      in pursuance of those of Mr. Canton, 294.
      on a silver cann, 307.
      on the velocity of the electric fluid, 327, 329, 330.
      for producing cold by evaporation, 344.
      on the different effects of electricity, 357.
      by lord Charles Cavendish, 348.
      on the tourmalin, 371.
      to show the utility of long pointed rods to houses, 389.
      on amber, 403 _et seq._
      on the Leyden phial, 434.
      on different coloured cloths, ii. 108, 109.
      on the sailing of boats, 160.

  _Exportation_ of gold and silver, observations on, ii. 416.

  _Exports_ to North America and the West Indies, iii. 127, 128.
      to Pensylvania, 129, 250.
      from ditto, 250.

  _Eye_, retains the images of luminous objects, ii. 340.

  F.

  _Facts_, should be ascertained before we attempt to account for them,
               ii. 96.

  _Family_ of Franklin, account of, i. 5. _et seq._

  _Famine_, how provided against in China, ii. 407.

  _Fanning_, how it cools, ii. 87.

  _Farmers_, remonstrance in behalf of, ii. 420.

  _Federal_ constitution, speech on, iii. 416.

  _Felons_, transportation of, to America, highly disagreeable to the
               inhabitants, iii. 235.

  _Fermenting_ liquors, their steam deleterious, ii. 59.

  Fire, not destroyed by water, but dispersed, i. 172.
      makes air specifically lighter, 206.
      exists in all bodies, 214.
      common and electrical, exist together, _ibid._
      a region of, above our atmosphere, 257, ii. 124.
      many ways of kindling it, i. 356.
      exists in a solid or quiescent state in substances, _ibid._ ii. 80,
               122.
      recovers its fluidity by combustion, _ibid._
      is a fluid permeating all bodies, 76.
      conductors of, are also best conductors of the electric fluid, _ibid._
          difference between, and electrical conductors, 77.
      how diffused through substances, 78.
      how generated in animated bodies, 79.
      theory of, 122.
      a fixed and permanent quantity of, in the universe, 123.
      its properties, 227.
      electrical, see _Electrical_.

  _Fire-companies_, numerous at Philadelphia, i. 103.

  _Fire-places_, Pensylvanian, account of, ii. 225.
      large and open, inconvenient, 228.
      hollow backed, by Gauger, 232.
      Staffordshire, 285.
      an ingenious one for serving two rooms, 296.