Experiments and Observations on Electricity Made at Philadelphia in America

By Benjamin Franklin

Page 27

motion, and leaping
from body to body, or from particle to particle thro' the air. When it
passes thro' dense bodies 'tis unseen. When a wire makes part of the
circle, in the explosion of the electrical phial, the fire, though in great
quantity, passes in the wire invisibly: but in passing along a chain, it
becomes visible as it leaps from link to link. In passing along
leaf-gilding 'tis visible: for the leaf-gold is full of pores; hold a leaf
to the light and it appears like a net; and the fire is seen in its leaping
over the vacancies.--And as when a long canal filled with still water is
opened at one end, in order to be discharged, the motion of the water
begins first near the opened end, and proceeds towards the close end, tho'
the water itself moves from the close towards the opened end: so the
electrical fire discharged into the polar regions, perhaps from a thousand
leagues length of vaporiz'd air, appears first where 'tis first in motion,
_i. e._ in the most northern part, and the appearance proceeds southward,
tho' the fire really moves northward. This is supposed to account for the
_Aurora Borealis_.

41. When there is great heat on the land, in a particular region (the sun
having shone on it perhaps several days, while the surrounding countries
have been screen'd by clouds) the lower air is rarified and rises, the
cooler denser air above descends; the clouds in that air meet from all
sides, and join over the heated place; and if some are electrified, others
not, lightning and thunder succeed, and showers fall. Hence thunder-gusts
after heats, and cool air after gusts; the water and the clouds that bring
it, coming from a higher and therefore a cooler region.

42. An electrical spark, drawn from an irregular body at some distance is
scarce ever strait, but shows crooked and waving in the air. So do the
flashes of lightning; the clouds being very irregular bodies.

43. As electrified clouds pass over a country, high hills and high trees,
lofty towers, spires, masts of ships, chimneys, _&c._ as so many
prominencies and points, draw the electrical fire, and the whole cloud
discharges there.

44. Dangerous, therefore, is it to take shelter under a tree during a
thunder-gust. It has been fatal to many, both men and beasts.

45. It is safer to be in the open field for another reason. When the
clothes are wet, if a flash in its way to the ground should strike your
head, it will run in the water over the

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Text Comparison with The Complete Works in Philosophy, Politics and Morals of the late Dr. Benjamin Franklin, Vol. 2 [of 3]

Page 1
1 On water-spouts 11 The same subject continued 13 Water-spouts and whirlwinds compared 19 Description of a water-spout at Antigua 34 Shooting stars 36 Water-spouts and whirlwinds 37 Observations on the meteorological paper; by a gentleman in Connecticut 45 Observations in answer to the foregoing,.
Page 7
--Modesty in disputation 317 Covering houses with copper 318 On the same subject 320 Paper referred to in the preceding letter 322 Magical square of squares 324 Magical circle 328 New musical instrument composed of glasses 330 Best mediums for conveying sound 335 On the.
Page 54
from the gate backwards to the head of the canal.
Page 68
I am persuaded, from several instances happening within my knowledge, that they do not bear cold weather so well as the whites; they will perish when exposed to a less degree of it, and are more apt to have their limbs frostbitten; and may not this be from the same cause? Would not the earth grow much hotter under the summer-sun, if a constant evaporation from its surface, greater as the sun shines stronger, did not, by tending to cool it; balance, in some degree, the warmer effects of the sun's rays? Is it not owing to the constant evaporation from the surface of every leaf, that trees, though shone on by the sun, are always, even the leaves themselves, cool to our sense? at least much cooler than they would otherwise be? May it not be owing to this, that fanning ourselves when warm, does really cool us, though the air is itself warm that we drive with the fan upon our faces; for the atmosphere round, and next to our bodies, having imbibed as much of the perspired vapour as it can well contain, receives no more, and the evaporation is therefore checked and retarded, till we drive away that atmosphere, and bring drier air in its place, that will receive the vapour, and thereby facilitate and increase the evaporation? Certain it is, that mere blowing of air on a dry body does not cool it, as any one may satisfy himself, by blowing with a bellows on the dry ball of a thermometer; the mercury will not fall; if it moves at all, it rather rises, as being.
Page 71
But this opinion takes it for granted that all water was originally fresh, of which we can have no proof.
Page 109
Being puzzled with the differing appearance, I at last pointed it out to our captain, and asked him the meaning of it.
Page 129
He built a double vessel, to serve as a packet boat between England and Ireland.
Page 132
I do not know that the reason has hitherto been given.
Page 136
The first is to be formed, and to be used in the water on almost the same principles with those of a paper kite used in the air.
Page 156
| of | of | | |ance | N.
Page 160
| West.
Page 169
I will, however, take this opportunity of repeating, those particulars to you, which I mentioned in our last conversation, as, by perusing them at your leisure, you may possibly imprint them so in your memory as on occasion to be of some use to you.
Page 261
Perhaps this fact is not exactly related: but if it is, would not one imagine from it, that the rarer the air, the greater sound might be produced in it from the same cause? 5.
Page 267
I am afraid you will hardly take my word for this, and therefore I must endeavour to support it by proof.
Page 271
It is, perhaps, owing to its being written in French, that Voltaire's Treatise on Toleration has had so sudden and so great an effect on the bigotry of Europe, as almost entirely to disarm it.
Page 292
Where the judgment is not ripe enough for forming new essays, let the sentiments of a Spectator be given, and required to be clothed in the scholar's own words; or the circumstances of some good story, the scholar to find expression.
Page 305
The rudeness of ancient military times and the fury of more modern enthusiastic ones are worn off; even the spirit of forensic contention is astonishingly diminished, all marks of manners softening; but luxury and corruption have taken their places, and seem the inseparable companions of commerce and the arts.
Page 309
, to those remote regions, which are destitute of them, and to bring from thence such productions, as can be cultivated in this kingdom to the advantage of society, in a ship under the command of Alexander Dalrymple.
Page 362
_Dreams_, art of procuring pleasant ones, iii.
Page 388
medical effects of, _ibid.