Heroes of Science: Physicists Part 5

"And the water forced out at one end of the tube is not the very same water that was forced in at the other end at the same time; it was only one motion at the same time.

"The long wire, made use of in the experiment to discover the velocity of the electric fluid, is itself filled with what we call its natural quant.i.ty of that fluid, before the hook of the Leyden bottle is applied at one end of it.

"The outside of the bottle being at the time of such application in contact with the other end of the wire, the whole quant.i.ty of electric fluid contained in the wire is, probably, put in motion at once.

"For at the instant the hook, connected with the inside of the bottle, _gives out_, the coating or outside of the bottle _draws in_, a portion of that fluid....

"So that this experiment only shows the extreme facility with which the electric fluid moves in metal; it can never determine the velocity.

"And, therefore, the proposed experiment (though well imagined and very ingenious) of sending the spark round through a vast length of s.p.a.ce, by the waters of Susquehannah, or Potowmack, and Ohio, would not afford the satisfaction desired, though we could be sure that the motion of the electric fluid would be in that tract, and not underground in the wet earth by the shortest way."

In his investigations of the source of electricity in thunder-clouds, Franklin tried an experiment which has been frequently repeated with various modifications. Having insulated a large bra.s.s plate which had been previously heated, he sprinkled water upon it, in order, if possible, to obtain electricity by the evaporation of the water, but no trace of electrification could be detected.

During his visit to England, Franklin wrote many letters to Mr.

Kinnersley and others on philosophical questions, but they consisted mainly of accounts of the work done by other experimenters in England, his public business occupying too much of his attention to allow him to conduct investigations for himself. In one of his letters, speaking of Lord Charles Cavendish, he says:--

It were to be wished that this n.o.ble philosopher would communicate more of his experiments to the world, as he makes many, and with great accuracy.

When the controversy between the relative merits of points and k.n.o.bs for the terminals of lightning-conductors arose, Franklin wrote to Mr.

Kinnersley:--

Here are some electricians that recommend k.n.o.bs instead of points on the upper end of the rods, from a supposition that the points invite the stroke. It is true that points draw electricity at greater distances in the gradual silent way; but k.n.o.bs will draw at the greatest distance a stroke. There is an experiment which will settle this. Take a crooked wire of the thickness of a quill, and of such a length as that, one end of it being applied to the lower part of a charged bottle, the upper may be brought near the ball on the top of the wire that is in the bottle. Let one end of this wire be furnished with a k.n.o.b, and the other may be gradually tapered to a fine point.

When the point is presented to discharge the bottle, it must be brought much nearer before it will receive the stroke than the k.n.o.b requires to be. Points, besides, tend to repel the fragments of an electrical cloud; k.n.o.bs draw them nearer. An experiment, which I believe I have shown you, of cotton fleece hanging from an electrized body, shows this clearly when a point or a k.n.o.b is presented under it.

The following quotation from Franklin's paper on the method of securing buildings and persons from the effects of lightning is worthy of attention, for of late years a good deal of money has been wasted in providing insulators for lightning-rods. A few years ago the vicar and churchwardens of a Lincolns.h.i.+re parish were strongly urged to go to the expense of insulating the conductor throughout the whole height of the very lofty tower and spire of their parish church. Happily they were wise enough to send the lightning-rod man about his business. But this is not the only case which has come under the writer's notice, showing that there is still a widespread impression that lightning-conductors should be carefully insulated. Franklin says:--

"The rod may be fastened to the wall, chimney, etc., with staples of iron. The lightning will not leave the rod (a good conductor) to pa.s.s into the wall (a bad conductor) through these staples. It would rather, if any were in the wall, pa.s.s out of it into the rod, to get more readily by that conductor into the earth."[2]

[Footnote 2: See p. 141.]

The conditions to be secured in a lightning-conductor are, firstly, a sharp point projecting above the highest part of the building, and gilded to prevent corrosion; secondly, metallic continuity from the point to the lower end of the conductor; and, thirdly, a good earth-contact. The last can frequently be secured by soldering the conductor to iron water-pipes underground. Where these are not available, a copper plate, two or three feet square, imbedded in clay or other damp earth, will serve the purpose. The method of securing a building which is erected on granite or other foundation affording no good earth-connection, will be referred to in a subsequent biographical sketch.

The controversy of points _versus_ k.n.o.bs was again revived in London when Franklin was in Paris, and the War of Independence had begun.

Franklin was consulted on the subject, the question having arisen in connection with the conductor at the palace. His reply was characteristic.

"As to my writing anything on the subject, which you seem to desire, I think it not necessary, especially as I have nothing to add to what I have already said upon it in a paper read to the committee who ordered the conductors at Purfleet, which paper is printed in the last French edition of my writings.

"I have never entered into any controversy in defence of my philosophical opinions. I leave them to take their chance in the world. If they are _right_, truth and experience will support them; if _wrong_, they ought to be refuted and rejected. Disputes are apt to sour one's temper and disturb one's quiet. I have no private interest in the reception of my inventions by the world, having never made, nor proposed to make, the least profit by any of them. The king's changing his _pointed_ conductors for _blunt_ ones is, therefore, a matter of small importance to me. If I had a wish about it, it would be that he had rejected them altogether as ineffectual. For it is only since he thought himself and family safe from the thunder of Heaven, that he dared to use his own thunder in destroying his innocent subjects."

The paper referred to was read before "the committee appointed to consider the erecting conductors to secure the magazines at Purfleet,"

on August 27, 1772. It described a variety of experiments clearly demonstrating the effect of points in discharging a conductor. This was a committee of the Royal Society, to whom the question had been referred on account of Dr. Wilson's recommendation of a blunt conductor. The committee decided in favour of Franklin's view, and when, in 1777, the question was again raised and again referred to a committee of the Royal Society, the decision of the former committee was confirmed, "conceiving that the experiments and reasons made and alleged to the contrary by Mr. Wilson are inconclusive."

Though Franklin's scientific reputation rests mainly on his electrical researches, he did not leave other branches of science untouched.

Besides his work on atmospheric electricity, he devoted a great deal of thought to meteorology, especially to the vortical motion of waterspouts. The Gulf-stream received a share of his attention. His improvements in fireplaces have already been noticed; the cure of smoky chimneys was the subject of a long paper addressed to Dr.

Ingenhousz, and of some other letters. One of his experiments on the absorption of radiant energy has been deservedly remembered.

"My experiment was this: I took a number of little square pieces of broad-cloth from a tailor's pattern-card, of various colours. There were black, deep blue, lighter blue, green, purple, red, yellow, white, and other colours or shades of colours. I laid them all out upon the snow in a bright, sun-s.h.i.+ny morning. In a few hours (I cannot now be exact as to the time) the black, being warmed most by the sun, was sunk so low as to be below the stroke of the sun's rays; the dark blue almost as low, the lighter blue not quite so much as the dark, the other colours less as they were lighter; and the quite white remained on the surface of the snow, not having entered it at all.

"What signifies philosophy that does not apply to some use? May we not learn from hence that black clothes are not so fit to wear in a hot, sunny climate or season, as white ones?"

Franklin knew much about electricity, but his knowledge of human nature was deeper still. This appears in all his transactions. His political economy was, perhaps, not always sound, but his judgment of men was seldom at fault.

"Finally, there seem to be but three ways for a nation to acquire wealth. The first is by _war_, as the Romans did, in plundering their conquered neighbour: this is _robbery_. The second by _commerce_, which is generally _cheating_. The third by _agriculture_, the only _honest way_, wherein man receives a real increase of the seed thrown into the ground, in a kind of continual miracle wrought by the hand of G.o.d in his favour, as a reward for his innocent life and his virtuous industry."

When Franklin reached London in 1757 he took up his abode with Mrs.

Margaret Stevenson, in Craven Street, Strand. For Mrs. Stevenson and her daughter Mary, then a young lady of eighteen, he acquired a sincere affection, which continued throughout their lives. Miss Stevenson spent much of her time with an aunt in the country, and some of Franklin's letters to her respecting the conduct of her "higher education" are among the most interesting of his writings. Miss Stevenson treated him as a father, and consulted him on every question of importance in her life. When she was a widow and Franklin eighty years of age, he urged upon her to come to Philadelphia, for the sake of the better prospects which the new country offered her boys. In coming to England, Franklin brought with him his son William, who entered the Middle Temple, but he left behind his only daughter, Sarah, in charge of her mother. To his wife and daughter he frequently sent presents from London, and his letters to Mrs. Franklin give a pretty full account of all his doings while in England. During his visit he received the honorary degrees of D.C.L. from the University of Oxford, and LL.D. from that of Edinburgh. At Cambridge he was sumptuously entertained. In August, 1762, he started again for America, and reached Philadelphia on November 1, after an absence of five years. His son William had shortly before been appointed Governor of New Jersey. From this time William Franklin became very much the servant of the proprietaries and of the English Government, but no offer of patronage produced any effect on the father.

Franklin's stay in America was of short duration, but while there he was mainly instrumental in quelling an insurrection in Pennsylvania.

He made a tour of inspection through the northern colonies in the summer of 1763, to regulate the post-offices. The disorder just referred to in the province caused the governor, as well as the a.s.sembly, to determine on the formation of a militia. A committee, of which Franklin was a member, drew up the necessary bill. The governor claimed the sole power of appointing officers, and required that trials should be by court-martial, some offences being punishable with death. The a.s.sembly refused to agree to these considerations. The ill feeling was increased by the governor insisting on taxing all proprietary lands at the same rate as uncultivated land belonging to other persons, whether the proprietary lands were cultivated or not.

The a.s.sembly, before adjourning, expressed an opinion that peace and happiness would not be secured until the government was lodged directly in the Crown. When the a.s.sembly again met, pet.i.tions to the king came in from more than three thousand inhabitants. In the mean while the British Ministry had proposed the Stamp Act, which was similar in principle to the English Stamp Act, which requires that all agreements, receipts, bills of exchange, marriage and birth certificates, and all other legal doc.u.ments should be provided with an inland revenue stamp of a particular value, in order that they might be valid. As soon as the a.s.sembly was convened, it determined to send Franklin to England, to take charge of a pet.i.tion for a change of government. The merchants subscribed 1100 towards his expenses in a few hours, and in twelve days he was on his journey, being accompanied to the s.h.i.+p, a distance of sixteen miles, by a cavalcade of three hundred of his friends, and in thirty days he reached London. Arrived in London, he at once took up his abode in his old lodgings with Mrs.

Stevenson. He was a master of satire, equalled only by Swift, and during the quarrels which preceded the War of Independence, as well as during the war, he made good use of his powers in this respect.

Articles appeared in some of the English papers tending to raise an alarm respecting the compet.i.tion of the colonies with English manufacturers. Franklin's contribution to the discussion was a caricature of the English press writers.

"It is objected by superficial readers, who yet pretend to some knowledge of those countries, that such establishments [manufactories for woollen goods, etc.] are not only improbable, but impossible, for that their sheep have but little wool, not in the whole sufficient for a pair of stockings a year to each inhabitant; that, from the universal dearness of labour among them, the working of iron and other materials, except in a few coa.r.s.e instances, is impracticable to any advantage.

"Dear sir, do not let us suffer ourselves to be amused with such groundless objections. The very tails of the American sheep are so laden with wool that each has a little car or waggon on four little wheels to support and keep it from trailing on the ground. Would they caulk their s.h.i.+ps, would they even litter their horses with wool, if it were not both plenty and cheap? And what signifies the dearness of labour, when an English s.h.i.+lling pa.s.ses for five and twenty? Their engaging three hundred silk throwsters here in one week for New York was treated as a fable, because, forsooth, they have 'no silk there to throw!' Those who make this objection perhaps do not know that, at the same time, the agents for the King of Spain were at Quebec, to contract for one thousand pieces of cannon to be made there for the fortification of Mexico, and at New York engaging the usual supply of woollen floor-carpets for their West India houses. Other agents from the Emperor of China were at Boston, treating about an exchange of raw silk for wool, to be carried in Chinese junks through the Straits of Magellan.

"And yet all this is as certainly true as the account said to be from Quebec in all the papers of last week, that the inhabitants of Canada are making preparations for a cod and whale fishery this summer in the upper Lakes. Ignorant people may object that the upper Lakes are fresh, and that cod and whales are salt-water fish; but let them know, sir, that cod, like other fish when attacked by their enemies, fly into any water where they can be safest; that whales, when they have a mind to eat cod, pursue them wherever they fly; and that the grand leap of the whale in the chase up the Falls of Niagara is esteemed, by all who have seen it, as one of the finest spectacles in nature."

One of Franklin's chief objects in coming to England was to prevent the pa.s.sing of Mr. Grenville's bill, previously referred to as the Stamp Act. The colonists urged that they had always been liberal in their votes, whenever money was required by the Crown, and that taxation and representation must, in accordance with the British const.i.tution, go hand-in-hand, so that the English Parliament had no right to raise taxes in America, so long as the colonists were unrepresented in Parliament. "Had Mr. Grenville, instead of that act, applied to the king in Council for such requisitional letters [_i.e._ requests to the a.s.semblies for voluntary grants], to be circulated by the Secretary of State, I am sure he would have obtained more money from the colonies by their voluntary grants than he himself expected from the sale of stamps. But he chose compulsion rather than persuasion, and would not receive from their good will what he thought he could obtain without it." The Stamp Act was pa.s.sed, stamps were printed, distributors were appointed, but the colonists would have nothing to do with the stamps. The distributors were compelled to resign their commissions, and the captains of vessels were forbidden to land the stamped paper. The cost of printing and distributing amounted to 12,000; the whole return was about 1500, from Canada and the West Indies.

The pa.s.sing of the Stamp Act was soon followed by a change of Ministry, when the question again came before Parliament. Franklin submitted to a long examination before a Committee of the whole House.

The feeling prevalent in America respecting the Stamp Act may be inferred from some of his answers.

"31. _Q._ Do you think the people of America would submit to pay the stamp duty if it was moderated?

"_A._ No, never, unless compelled by force of arms.

"36. _Q._ What was the temper of America towards Great Britain before the year 1763?[3]

[Footnote 3: The date of the Sugar Act.]

"_A._ The best in the world. They submitted willingly to the government of the Crown, and paid, in their courts, obedience to the Acts of Parliament. Numerous as the people are in the several old provinces, they cost you nothing in forts, citadels, garrisons, or armies to keep them in subjection. They were governed by this country at the expense only of a little pen, ink, and paper; they were led by a thread. They had not only a respect, but an affection, for Great Britain--for its laws, its customs and manners, and even a fondness for its fas.h.i.+ons, that greatly increased the commerce. Natives of Britain were always treated with particular regard; to be an _Old-Englandman_ was, of itself, a character of some respect, and gave a kind of rank among us.

"37. _Q._ And what is their temper now?

"_A._ Oh, very much altered.

"50. _Q._ Was it an opinion in America before 1763 that the Parliament had no right to lay taxes and duties there?

"_A._ I never heard any objection to the right of laying duties to regulate commerce; but a right to lay internal taxes was never supposed to be in Parliament, as we are not represented there.

"59. _Q._ You say the colonies have always submitted to external taxes, and object to the right of Parliament only in laying internal taxes; now, can you show that there is any kind of difference between the two taxes to the colony on which they may be laid?

"_A._ I think the difference is very great. An _external_ tax is a duty laid on commodities imported; that duty is added to the first cost and other charges on the commodity, and, when it is offered to sale, makes a part of the price. If the people do not like it at that price, they refuse it; they are not obliged to pay it. But an _internal_ tax is forced upon the people without their consent, if not laid by their own representatives. The Stamp Act says we shall have no commerce, make no exchange of property with each other, neither purchase, nor grant, nor recover debts; we shall neither marry nor make our wills, unless we pay such and such sums; and thus it is intended to extort our money from us, or ruin us by the consequences of refusing to pay it.

"61. _Q._ Don't you think cloth from England absolutely necessary to them?