Memoirs of Benjamin Franklin; Written by Himself. [Vol. 2 of 2] With his Most Interesting Essays, Letters, and Miscellaneous Writings; Familiar, Moral, Political, Economical, and Philosophical, Selected with Care from All His Published Productions, and Comprising Whatever Is Most Entertaining and Valuable to the General Reader

By Benjamin Franklin

Page 208

that which appears a water-spout at sea does sometimes, in its
progressive motion, meet with and pass over land, and there produce all
the phenomena and effects of a whirlwind, it should thence seem still
more evident that a whirlwind and a spout are the same. I send you,
herewith, a letter from an ingenious physician of my acquaintance, which
gives one instance of this, that fell within his observation.

A fluid, moving from all points horizontally towards a centre, must, at
that centre, either ascend or descend. Water being in a tub, if a hole
be opened in the middle of the bottom, will flow from all sides to the
centre, and there descend in a whirl. But air flowing on and near the
surface of land or water, from all sides towards a centre, must at that
centre ascend, the land or water hindering its descent.

If these concentring currents of air be in the upper region, they may,
indeed, descend in the spout or whirlwind; but then, when the united
current reached the earth or water, it would spread, and, probably, blow
every way from the centre. There may be whirlwinds of both kinds, but
from the commonly observed effects I suspect the rising one to be the
most common: when the upper air descends, it is, perhaps, in a greater
body, extending wider, as in our thunder-gusts, and without much
whirling; and, when air descends in a spout or whirlwind, I should
rather expect it would press the roof of a house _inward_, or force _in_
the tiles, shingles, or thatch, force a boat down into the water, or a
piece of timber into the earth, than that it would lift them up and
carry them away.

It has so happened that I have not met with any accounts of spouts that
certainly descended; I suspect they are not frequent. Please to
communicate those you mention. The apparent dropping of a pipe from the
clouds towards the earth or sea, I will endeavour to explain hereafter.

The augmentation of the cloud, which, as I am informed, is generally,
if not always the case, during a spout, seems to show an ascent rather
than a descent of the matter of which such cloud is composed; for a
descending spout, one would expect, should diminish a cloud. I own,
however, that cold air, descending, may, by condensing the vapours in a
lower region, form and increase clouds; which, I think, is generally the
case in our common thunder-gusts, and, therefore, do not lay great
stress on this argument.

Whirlwinds and spouts are not always,

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Text Comparison with Experiments and Observations on Electricity Made at Philadelphia in America

Page 4
Fix a wire in the lead, with which the bottom of the bottle is armed, (_d_) so as that bending upwards, its ring-end may be level with the top or ring-end of the wire in the cork (_e_), and at three or four inches distance.
Page 6
The room should be darkened.
Page 8
--But now I need only mention some particulars not hinted in that piece, with our reasonings thereupon; though perhaps the latter might well enough be spared.
Page 9
Hence have arisen some new terms among us: we say, _B_, (and bodies like circumstanced) is electrised _positively_; _A_, _negatively_.
Page 10
_--We electrise a person twenty or more times running, with a touch of the finger on the wire, thus: He stands on wax.
Page 16
If the picture were highly charged, the consequence might perhaps be as fatal as that of high-treason; for when the spark is taken through a quire of paper laid on the picture, by means of a wire communication, it makes a fair hole through every sheet, that is, through 48 leaves, (though.
Page 17
A small upright shaft of wood passes at right angles through a thin round board, of about twelve inches diameter, and turns on a sharp point of iron fixed in the lower end, while a strong wire in the upper-end passing thro' a small hole in a thin brass plate, keeps the shaft truly vertical.
Page 19
As the glass is thickest near the orifice, I suppose the lower half, which being gilt was electrified, and gave the shock, did not exceed two grains; for it appeared, when broke, much thinner than the upper half.
Page 22
9.
Page 26
Two gun-barrels united, and as highly electrified, will give a spark at a still greater distance.
Page 27
So do the flashes of lightning; the clouds being very irregular bodies.
Page 30
attract and retain it strongest, and contain the greatest quantity.
Page 32
From a cube it is more easily drawn at the corners than at the plane sides, and so from the angles of a body of any other form, and still most easily from the angle that is most acute.
Page 37
) big enough to contain a man and an electrical stand.
Page 41
You may make this figure so acute below and blunt above, as to need no under plate, it discharging fast enough into the air.
Page 46
Put a wire into the tube, the inward end in contact with the non-electric lining, so it will represent the _Leyden_ bottle.
Page 47
If you offer a quantity to one end of a long rod of metal, it receives it, and when it enters, every particle that was before in the rod, pushes its neighbour quite to the further end, where the overplus is discharg'd; and this instantaneously where the rod is part of the circle in the experiment of the shock.
Page 50
But if the fire, with which the inside surface is surcharged, be so much precisely as is wanted by the outside surface, it will pass round through the wire fixed to the wax handle, restore the equilibrium in the glass, and make no alteration in the state of the prime conductor.
Page 51
16.
Page 54
[12] See farther experiments, s 15.