have succeeded in small, in large have failed. It is true, that in mechanics this has sometimes happened. But, when it is considered, that we owe our first knowledge of the nature and operations of lightning to observations on such small experiments; and that, on carefully comparing the most accurate accounts of former facts, and the exactest relations of those that have occurred since, the effects have surprisingly agreed with the theory; it is humbly conceived, that in natural philosophy, in this branch of it at least, the suggestion has not so much weight; and that the farther new experiments, now adduced in recommendation of long, sharp-pointed rods, may have some claim to credit and consideration.

It has been urged, too, that, though points may have considerable effects on a small prime conductor at small distances; yet, on great clouds and at great distances, nothing is to be expected from them. To this it is answered, that in those small experiments it is evident the points act at a greater than the striking distance; and, in the large way, their service is only expected where there is such nearness of the cloud as to endanger a stroke; and there, it cannot be doubted, the points must have some effect. And, if the quantity discharged by a single pointed rod may be so considerable as I have shown it, the quantity discharged by a number will be proportionably greater.

But this part of the theory does not depend alone on small experiments. Since the practice of erecting pointed rods in America (now near twenty years), five of them have been struck by lightning, namely, Mr. Raven's and Mr. Maine's in South Carolina, Mr. Tucker's in Virginia, Mr. West's and Mr. Moulder's in Philadelphia. Possibly there may have been more, that have not come to my knowledge. But, in

every one of these, the lightning did not fall upon the body of the house, but precisely on the several points of the rods; and, though the conductors were sometimes not sufficiently large and complete, was conveyed into the earth, without any material damage to the buildings. Facts then in great, as far as we have them authenticated, justify the opinion that is drawn from the experiments in small, as above related.

It has also been objected, that, unless we knew the quantity that might possibly be discharged at one stroke from the clouds, we cannot be sure we have provided sufficient conductors; and therefore cannot depend on their conveying away all that may fall on their points. Indeed we have nothing to form a judgment by in this, but past facts; and we know of no instance, where a complete conductor to the moist earth has been insufficient, if half an inch in diameter. It is probable, that many strokes of lightning have been conveyed through the common leaden pipes affixed to houses to carry down the water from the roof to the ground; and there is no account of such pipes being melted and destroyed, as must sometimes have happened, if they had been insufficient. We can, then, only judge of the dimensions proper for a conductor of lightning, as we do of those proper for a conductor of rain, by past observations. And, as we think a pipe of three inches bore sufficient to carry off the rain that falls on a square of twenty feet, because we never saw such a pipe glutted by any shower; so we may judge a conductor of an inch diameter more than sufficient for any stroke of lightning that will fall on its point. It is true, that, if another deluge should happen wherein the windows of heaven are to be opened, such pipes may be unequal to the falling quantity; and, if God for our sins should think fit to rain fire upon us, as upon some cities of old, it is

not expected that our conductors, of whatever size, should secure our houses against a miracle. Probably, as water drawn up into the air and there forming clouds, is disposed to fall again in rain by its natural gravity, as soon as a number of particles sufficient to make a drop can get together; so, when the clouds are (by whatever means) over or under charged with the electric fluid to a degree sufficient to attract them towards the earth, the equilibrium is restored, before the difference becomes great beyond that degree. Mr. Lane's electrometer, for limiting precisely the quantity of a shock that is to be administered in a medical view, may serve to make this more easily intelligible. The discharging knob does by a screw approach the conductor to the distance intended, but there remains fixed. Whatever power there may be in the glass globe to collect the fulminating fluid, and whatever capacity of receiving and accumulating it there may be in the bottle or glass jar, yet neither the accumulation nor the discharge ever exceeds the destined quantity. Thus, were the clouds always at a certain fixed distance from the earth, all discharges would be made when the quantity accumulated was equal to the distance. But there is a circumstance, which, by occasionally lessening the distance, lessens the discharge; to wit, the movableness of the clouds, and their being drawn nearer to the earth by attraction when electrified; so that discharges are thereby rendered more frequent and of course less violent. Hence, whatever the quantity may be in nature, and whatever the power in the clouds of collecting it, yet an accumulation and force beyond what mankind has hitherto been acquainted with is scarce to be expected.

August, 27, 1772.

B. F.

SIR,

600. TO REV. WILLIAM SMITH (A. P. S.)

London, Aug 22, 1772

I received yours of May 16 with the Box of Books, and have already delivered and forwarded most of them as directed. I supply'd D' Fothergill with the wanting Sheet. I approve much of the Letter's being in English. I forwarded your Letter to Mr. White, Son of Taylor White, Esq' late Treasurer of the Foundling Hospital (now deceas'd) but he has not call'd for the Book. I am glad to hear of your Success at South Carolina, and that the College flourishes. I send enclos'd a Pamphlet on a new Discovery that makes some Noise here. With my best Wishes of Prosperity to the Society and Thanks for the Number of Books they have sent me, which I shall endeavour to dispose of to their Credit, I am, Sir,

Your most obedt hum1 Servant

B. FRANKLIN.

601. TO ANTHONY BENEZET1

(L. C.)

London, August 22: 1772.

DEAR FRIEND,

I made a little extract from yours of April 27, of the number of slaves imported and perishing, with some close remarks on the hypocrisy of this country, which encourages such a detestable commerce by laws for promoting the Guinea trade;

1 Anthony Benezet (1713–1784) was born in St. Quentin, France, but lived fifty-three years in Philadelphia. He belonged to the Society of Friends and devoted his life to the abolition of the slave trade. - ED.

while it piqued itself on its virtue, love of liberty, and the equity of its courts, in setting free a single negro. This was inserted in the London Chronicle, of the 20th of June last.

I thank you for the Virginia address, which I shall also publish with some remarks. I am glad to hear that the disposition against keeping negroes grows more general in North America. Several pieces have been lately printed here against the practice, and I hope in time it will be taken into consideration and suppressed by the legislature. Your labours have already been attended with great effects. I hope, therefore, you and your friends will be encouraged to proceed. My hearty wishes of success attend you, being ever, my dear friend, yours affectionately,

B. FRANKLIN.

602. TO JOHN BARTRAM1

London, August 22, 1772.

My dear old Friend, I received your kind letter of May 10. I am glad the Rhubarb Seed got safe to hand. I make no doubt of its Thriving well in our Country, where the Climate is the same with that of the Chinese Wall, just outside which it grows in plenty and of the best Quality. I shall be glad to know how you find the Juniper. I asked Solander about the Lucern Seed you wrote for. He could give me no Account of it, nor can I learn anything of it from others. You may rely upon my Friendship in recommending your Seeds. I send all that enquire of me about American Seeds to Mr. Freeman. He should advertise them when they come. 1 From the original in the Royal Museum, Salford, England. — ED.