if the barrel
were kept under water. This tin-foil is but about eighteen pence
sterling a pound, and is so extremely thin, that I imagine a pound of
it would line three or four powder-barrels.
I am, &c.
 Peter Franklin. _Editor._
_Of Lightning, and the Methods (now used in America) of securing
Buildings and Persons from its mischievous Effects._
Experiments made in electricity first gave philosophers a suspicion,
that the matter of lightning was the same with the electric matter.
Experiments afterwards made on lightning obtained from the clouds by
pointed rods, received into bottles, and subjected to every trial,
have since proved this suspicion to be perfectly well founded;
and that whatever properties we find in electricity, are also the
properties of lightning.
This matter of lightning, or of electricity, is an extreme subtile
fluid, penetrating other bodies, and subsisting in them, equally
When by any operation of art or nature, there happens to be a greater
proportion of this fluid in one body than in another, the body
which has most will communicate to that which has least, till the
proportion becomes equal; provided the distance between them be not
too great; or, if it is too great, till there be proper conductors to
convey it from one to the other.
If the communication be through the air without any conductor, a
bright light is seen between the bodies, and a sound is heard. In
our small experiments, we call this light and sound the electric
spark and snap; but in the great operations of nature, the light is
what we call _lightning_, and the sound (produced at the same time,
though generally arriving later at our ears than the light does to
our eyes) is, with its echoes, called _thunder_.
If the communication of this fluid is by a conductor, it may be
without either light or sound, the subtle fluid passing in the
substance of the conductor.
If the conductor be good and of sufficient bigness, the fluid passes
through it without hurting it. If otherwise, it is damaged or
All metals, and water, are good conductors.--Other bodies may become
conductors by having some quantity of water in them, as wood, and
other materials used in building, but not having much water in them,
they are not good conductors, and therefore are often damaged in the
Glass, wax, silk, wool, hair, feathers, and even wood, perfectly dry
are non-conductors: that is, they resist instead of facilitating the
passage of this subtle fluid.
When this fluid has an opportunity of passing through two conductors,
one good, and sufficient, as of
But if a man were taken up from latitude 40 (where suppose the earth's surface to move twelve miles per minute) and immediately set down at the equinoctial, without changing the motion he had, his heels would be struck up, he would fall westward.Page 29
Now, I suppose this whirl of air will, at first, be as invisible as the air itself, though reaching, in reality, from the water, to the region of cool air, in which our low summer thunder-clouds commonly float; but presently it will become visible at its extremities.Page 42
" But then if the air can support and take off but such a proportion of water, and it is necessary that water be so taken off from the lungs, I queried with myself how it is we can breathe in an air full of vapours, so full as that they continually precipitated.Page 67
For I remember well, that the desk, when I laid my arm upon it; a chair, when I sat down in it; and a dry shirt out of the drawer, when I put it on, all felt exceeding warm to me, as if they had been warmed before a fire.Page 87
6, he tells us, "that all this is likewise certain when taken the contrary way, viz.Page 104
When I was in England, the last time, you also made for me a little achromatic pocket telescope, the body was brass, and it had a round case (I think of thin wood) covered with shagrin.Page 111
Being about to show him the smoothing experiment on a little pond near his house, an ingenious pupil of his, Mr.Page 127
And as to water-casks mentioned above, since the quantity of them must be great in ships of war where the number of men consume a great deal of water every day, if it had been made a constant rule to bung them up as fast as they were emptied, and to dispose the empty casks in proper situations, I am persuaded that many ships which have been sunk in engagements, or have gone down afterwards, might with the unhappy people have been saved; as well as many of those which in the last war foundered, and were never heard of.Page 131
The first lost her bowsprit, but received little other damage.Page 132
Perhaps it may be this, that great part of the force employed contributes little to the motion.Page 173
_ **** I shall not attempt to explain why damp clothes occasion colds, rather than wet ones, because I doubt the fact; I imagine that neither the one nor the other contribute to this effect, and that the causes of colds are totally independent of wet and even of cold.Page 197
Chalk a line from one of its back corners round the plate to the other corner, that you may afterwards know its place when you come to fix it; and from those corners, two parallel lines to the back of the chimney: make marks also on each side, that you may know where the partition is to stand, which is to prevent any communication between the air and smoke.Page 216
This case is most frequent where the funnel is short, and the opening turned from the wind.Page 239
When the charcoal is well kindled, lay on it the sea-coals, observing not to choak the fire by putting on too much at first.Page 243
At length it occurred to me, that I and many others had seen the same thing thousands of times, in the conservation of the red coal formed in the snuff of a burning candle, which while envelloped in flame, and thereby prevented from the contact of passing air, is long continued and augments instead of diminishing, so that we are often obliged to remove it by the snuffers, or bend it out of the flame into the air, where it consumes presently to ashes.Page 268
mysterious art_, twice repeated; _magic charms can ne'er relieve you_, three times.Page 290
_The Third Class_ To be taught speaking properly and gracefully; which is near a-kin to good reading, and naturally follows it in the studies of youth.Page 308
Our seamen are equally bold, skilful, and hardy; dexterous in exploring the remotest regions, and ready to engage in voyages to unknown countries, though attended with the greatest dangers.Page 356
_British empire_, an union of several states, iii.Page 364
shock, observations on, 182.