the stroke it secures us from might have chanced, perhaps, but once in our lives, while it may relieve us a hundred times from those painful apprehensions, the latter may possibly, on the whole, contribute more to the happiness of mankind than the former.

Your kind wishes and congratulations are very obliging. I return them cordially; being, with great regard and esteem, my dear Sir, your affectionate friend and most obedient humble servant,

B. FRANKLIN.

Accounts from Carolina (mentioned in the foregoing Letter) of the Effects of Lightning on two of the Rods commonly affixed to Houses there, for securing them against Lightning.

Charleston, 1 November, 1760.

"It is some years since Mr. Raven's rod was struck by lightning. I hear an account of it was published at the time, but I cannot find it. According to the best information I can now get, he had fixed to the outside of his chimney a large iron rod, several feet in length, reaching above the chimney; and to the top of this rod the points were fixed. From the lower end of this rod, a small brass wire was continued down to the top of another iron rod driven into the earth. On the ground-floor in the chimney stood a gun, leaning against the back wall, nearly opposite to where the brass wire came down on the outside. The lightning fell upon the points, did no damage to the rod they were fixed to; but the brass wire, all down till it came opposite to the top of the gun-barrel, was destroyed.*

* A proof that it was not of sufficient substance to conduct with safety to itself (though with safety so far to the wall) so large a quantity of the electric fluid.

There the lightning made a hole through the wall, or back of the chimney, to get to the gun-barrel,* down which it seems to have passed, as, although it did not hurt the barrel, it damaged the butt of the stock, and blew up some bricks of the hearth. The brass wire below the hole in the wall remained good. No other damage, as I can learn, was done to the house. I am told the same house had formerly been struck by lightning, and much damaged, before these rods were invented."

Mr. William Maine's Account of the Effects of the Lightning on his Rod, dated at Indian Land, in South Carolina, August 28th, 1760.

"I had a set of electrical points, consisting of three prongs, of large brass wire tipt with silver, and perfectly sharp, each about seven inches long; these were riveted at equal distances into an iron nut about three quarters of an inch square, and opened at top equally to the distance of six or seven inches from point to point, in a regular triangle. This nut was screwed very tight on the top of an iron rod of about half an inch diameter, or the thickness of a common curtainrod, composed of several joints, annexed by hooks turned at the ends of each joint, and the whole fixed to the chimney of my house by iron staples. The points were elevated (a) six or seven inches above the top of the chimney; and the lower joint sunk three feet in the earth, in a perpendicular direction.

"Thus stood the points on Tuesday last, about five in the evening, when the lightning broke with a violent

* A more substantial conductor.

explosion on the chimney, cut the rod square off just under the nut, and, I am persuaded, melted the points, nut, and top of the rod, entirely up; as, after the most diligent search, nothing of either was found (b), and the top of the remaining rod was cased over with a congealed solder. The lightning ran down the rod, starting almost all the staples (c), and unhooking the joints without affecting the rod (d), except on the inside of each hook where the joints were coupled, the surface of which was melted (e), and left as cased over with solder. No part of the chimney was damaged (f), only at the foundation (g), where it was shattered almost quite round, and several bricks were torn out (h). Considerable cavities were made in the earth quite round the foundation, but most within eight or nine inches of the rod. It also shattered the bottom weather-board (i) at one corner of the house, and made a large hole in the earth by the corner post. On the other side of the chimney, it ploughed up several furrows in the earth, some yards in length. It ran down the inside of the chimney (k), carrying only soot with it, and filled the whole house with its flash (1), smoke, and dust. It tore up the hearth in several places (m), and broke some pieces of China in the buffet (n). A copper tea-kettle standing in the chimney was beat together, as if some great weight had fallen upon it (0); and three holes, each about half an inch diameter, melted through the bottom (p). What seems to me the most surprising is, that the hearth under the kettle was not hurt, yet the bottom of the kettle was drove inward, as if the lightning proceeded from under it upwards (9), and the cover was thrown to the middle of the floor (r). The fire-dogs, an iron loggerhead, an Indian pot, an earthen cup, and a cat were all in the chimney at the time unhurt, though a great part of the

hearth was torn up (s). My wife's sister, two children, and a negro wench were all who happened to be in the house at the time; the first and one child sat within five feet of the chimney, and were so stunned, that they never saw the lightning nor heard the explosion; the wench, with the other child in her arms, sitting at a greater distance, was sensible of both; though every one was so stunned that they did not recover for some time; however, it pleased God that no farther mischief ensued. The kitchen, at ninety feet distance, was full of negroes, who were all sensible of the shock; and some of them tell me, that they felt the rod about a minute after, when it was so hot that they could not bear it in hand."

Remarks by Benjamin Franklin.

THE foregoing very sensible and distinct account may afford a 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 313, 356.) 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. great body of matter near them would hinder their being easily brought into a negative state by the repul sive power of the electrized 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.

For the

(b) Nothing of the points, &c. could be found. This is a common effect. (See page 358.) 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 smoke and dissipated; but where the conductor is sufficiently large, the fluid passes in it without hurting it. Thus these three wires were destroyed, while the rod to which they were fixed, being of greater substance, remained unhurt; its end only, to which they were joined, being a little