The Complete Works in Philosophy, Politics and Morals of the late Dr. Benjamin Franklin, Vol. 1 [of 3]

By Benjamin Franklin

Page 252

good
deal of instruction relating to the nature and effects of lightning,
and to the construction and use of this instrument for averting the
mischiefs of it. Like other new instruments, this appears to have
been at first in some respects imperfect; and we find that we are, in
this as in others, to expect improvement from experience chiefly: but
there seems to be nothing in the account, that should discourage us
in the use of it; since at the same time that its imperfections are
discovered, the means of removing them are pretty easily to be learnt
from the circumstances of the account itself; and its utility upon
the whole is manifest.

One intention of the pointed rod, is, to _prevent_ a stroke of
lightning. (_See pages_ 283, 310.) But to have a better chance of
obtaining this end, the points should not be too near to the top
of the chimney or highest part of the building to which they are
affixed, but should be extended five or six feet above it; otherwise
their operation in silently drawing off the fire (from such fragments
of cloud as float in the air between the great body of cloud and
the earth) will be prevented. For the experiment with the lock of
cotton hanging below the electrified prime conductor shows, that a
finger under it, being a blunt body, extends the cotton, drawing its
lower part downwards; when a needle, with its point presented to the
cotton, makes it fly up again to the prime conductor; and that this
effect is strongest when as much of the needle as possible appears
above the end of the finger; grows weaker as the needle is shortened
between the finger and thumb; and is reduced to nothing when only a
short part below the point appears above the finger. Now it seems
the points of Mr. Maine's rod were elevated only (_a_) _six or seven
inches above the top of the chimney_; which, considering the bulk of
the chimney and the house, was too small an elevation. For the great
body of matter near them would hinder their being easily brought into
a negative state by the repulsive power of the electrised cloud,
in which negative state it is that they attract most strongly and
copiously the electric fluid from other bodies, and convey it into
the earth.

(_b_) _Nothing of the points, &c. could be found._ This is a common
effect. (_See page_ 312.) Where the quantity of the electric fluid
passing is too great for the conductor through which it passes, the
metal is either melted, or reduced to

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Text Comparison with 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

Page 0
CONTENTS OF THE SECOND VOLUME.
Page 11
--Salt Water rendered fresh.
Page 14
_ Work while it is called to-day, for you know not how much you may be hindered to-morrow.
Page 30
It is by the help of geometry the ingenious mariner is instructed how to guide a ship through the vast ocean, from one part of the.
Page 33
In general, mankind, since the improvement of cookery, eat about twice as much as nature requires.
Page 35
3.
Page 42
_ If I see one fond of appearance, or fine clothes, fine houses, fine furniture, fine equipages, all above his fortune, for which he contracts debts and ends his days in prison, _Alas!_ say I, _he has paid dear, very dear, for his whistle.
Page 44
" "True," said the farmer, "but you do not tell all the story.
Page 53
Let us now suppose this venerable insect, this _Nestor_ of _Hypania_, should, a little before his death, and about sunset, send for all his descendants, his friends and his acquaintances, out of the desire he may have to impart his last thoughts to them, and to admonish them with his departing breath.
Page 61
Two of our young hunters, having killed a deer, made a fire in the woods to broil some parts of it.
Page 90
Edward Mecom, July 27, 1727.
Page 136
He may have had them so long as to think them his own.
Page 148
I thought it therefore, well to communicate to him a copy of your letter which contains so many sensible and just observations on that subject.
Page 155
He's gone, and has not left behind him his fellow.
Page 181
I want to know whether your Philosophical Society received the second volume of our Transactions.
Page 182
Has the question, how came the earth by its magnetism, ever been considered? Is it likely that _iron ore_ immediately existed when this globe was at first formed; or may it not rather be supposed a gradual production of time? If the earth is at present magnetical, in virtue of the masses of iron ore contained in it, might not some ages pass before it had magnetic polarity? Since iron ore may exist without that polarity, and, by being placed in certain circumstances, may obtain it from an external cause, is it not possible that the earth received its magnetism from some such cause? In short, may not a magnetic power exist throughout our system, perhaps through all systems, so that if men could make a voyage in the starry regions, a compass might be of use? And may not such universal magnetism, with its uniform direction, be serviceable in keeping the diurnal revolution of a planet more steady to the same axis? Lastly, as the poles of magnets may be changed by the presence of stronger magnets, might not, in ancient times, the near passing of some large comet, of greater magnetic power than this globe of ours, have been a means of changing its poles, and thereby wrecking and deranging its surface, placing in different regions the effect of centrifugal force, so as to raise the waters of the sea in some, while they were depressed in others? Let me add another question or two, not relating indeed to magnetism, but, however, to the theory of the earth.
Page 187
He adds, that though the abyss be liable to those commotions in all parts, yet the effects are nowhere very remarkable except in those countries which are mountainous, and, consequently, stony or cavernous underneath; and especially where the disposition of the strata is such that those caverns open the abyss, and so freely admit and entertain the fire which, assembling therein, is the cause of.
Page 199
To the top of the upright stick of the cross is to be fixed a very sharp-pointed wire, rising a foot or more above the wood.
Page 209
The coldness of the upper region is manifested by the hail which sometimes falls from it in a hot day.
Page 236
Between the deepest and shallowest it appears to be somewhat more than one fifth.