Chapter 16

The flash was very great, and the crack as loud as a pistol; yet, my senses being instantly gone, I neither saw the one nor heard the other; nor did I feel the stroke on my hand, though I afterwards found it raised a round swelling where the fire entered, as big as half a pistol-bullet; by which you may judge of the quickness of the electrical fire, which by this instance seems to be greater than that of sound, light, or animal sensation.... I then felt what I know not how well to describe; a universal blow throughout my whole body from head to foot, which seemed within as well as without; after which the first thing I took notice of was a violent quick shaking of my body, which gradually remitting, my sense as gradually returned, and then I thought the bottles must be discharged, but could not conceive how, till at last I perceived the chain in my hand, and recollected what I had been about to do. That part of my hand and fingers, which held the chain, was left white, as though the blood had been driven out, and remained so eight or ten minutes after, feeling like dead flesh; and I had a numbness in my arms and the back of my neck, which continued till the next morning, but wore off. Nothing remains now of this shock, but a soreness in my breast-bone, which feels as if it had been bruised. I did not fall, but suppose I should have been knocked down, if I had received the stroke in my head. The whole was over in less than a minute.

On the second occasion, while making ready to give a healing shock to a paralytic, he received a charge through his own head. He did not see the flash, hear the report or feel the stroke.

When my Senses returned [he told Jan Ingenhousz], I found myself on the Floor. I got up, not knowing how that had happened. I then again attempted to discharge the Jars; but one of the Company told me they were already discharg'd,which I could not at first believe, but on Trial found it true. They told me they had not felt it, but they saw I was knock'd down by it, which had greatly surprised them. On recollecting myself, and examining my Situation, I found the Case clear. A small swelling rose on the Top of my Head, which continued sore for some Days; but I do not remember any other Effect good or bad.

One of Franklin's contemporaries, Professor Richmann, of St. Petersburg, did not fare so well; for a stroke of the lightning that he had allured from the clouds brought his life to an end. Priestley, however, seems to have regarded such a death as a form of euthanasia. At any rate, in speaking of this martyr of science in hisHistory of Electricityhe terms him "the justly envied Richmann."

After Franklin learned how to impound lightning, his intercourse with electricity was more familiar than ever.

In September, 1752 [he wrote to Collinson], I erected an iron rod to draw the lightning down into my house, in order to make some experiments on it, with two bells to give notice when the rod should be electrify'd: a contrivance obvious to every electrician.I found the bells rang sometimes when there was no lightning or thunder, but only a dark cloud over the rod; that sometimes, after a flash of lightning, they would suddenly stop; and, at other times, when they had not rang before, they would, after a flash, suddenly begin to ring; that the electricity was sometimes very faint, so that, when a small spark was obtain'd, another could not be got for some time after; at other times the sparks would follow extremely quick, and once I had a continual stream from bell to bell, the size of a crow quill: Even during the same gust there were considerable variations.In the winter following I conceived an experiment, to try whether the clouds were electrify'dpositivelyornegatively.

I found the bells rang sometimes when there was no lightning or thunder, but only a dark cloud over the rod; that sometimes, after a flash of lightning, they would suddenly stop; and, at other times, when they had not rang before, they would, after a flash, suddenly begin to ring; that the electricity was sometimes very faint, so that, when a small spark was obtain'd, another could not be got for some time after; at other times the sparks would follow extremely quick, and once I had a continual stream from bell to bell, the size of a crow quill: Even during the same gust there were considerable variations.

In the winter following I conceived an experiment, to try whether the clouds were electrify'dpositivelyornegatively.

The result of these experiments, conducted with Franklin's usual painstaking completeness, was the conclusion on his part that thunder-clouds are, as a rule, in a negativelyelectrical state, and that, therefore, generally speaking, they do not discharge electricity upon the earth, but receive it from the earth. For the most part, he said, "tis the earth that strikes into the clouds, and not the clouds that strike into the earth."

The thoroughness with which he addressed himself to the study of electricity was very marked. His investigation was as searching and minute as that of an anatomist engaged in the dissection of nervous tissue. Under his hands, the bare Leyden Jar became a teeming storehouse of instruction and amusement. He collected electricity from common objects by friction, he brought it down from the sky, he sought its properties in amber, in the tourmaline stone, in the body of the torpedo; he thought that he discerned it in the radiance of the Aurora Borealis. He put it through all its vagaries, juggled with it, teased it, cowed it until it confessed its kinship with the tempestuous heavens. He tested its destructive effects upon hens and turkeys, its therapeutic value to paralytic patients, its efficacy as a corrective of tough meat. He even, it is said, charged the railing under his windows with it to repel loafers standing about his front door. And, in his relations to electricity, as to everything else, his purposes were always those of practical utility. In one of his papers, he admits that he cannot tell why points possess the power of drawing off the electrical fire;

nor is it of much importance to us [he adds] to know the manner in which nature executes her laws. 'Tis enough if we know the laws themselves. 'Tis of real use to know that china left in the air unsupported will fall and break; buthowit comes to fall, andwhyit breaks, are matters of speculation. 'Tis a pleasure indeed to know them, but we can preserve our china without it.

He anticipated, or, in some instances, all but anticipated, several of the more important discoveries of modernelectrical science. He knew that, when a number of Leyden jars are connected up under certain conditions, the extent, to which each jar can be charged from a given source, varies inversely as the number of jars. For a time, he was puzzled by the fact that the light of a candle, or of a fire-coal, or of red-hot iron, would destroy the repellency between his electrified ball and shot, but that the light of the sun would not. But it was not long before he hit upon this ingenious explanation:

This different Effect probably did not arise from any difference in the light, but rather from the particles separated from the candle, being first attracted and then repelled, carrying off the electric matter with them; and from the rarefying the air, between the glowing coal or red-hot iron, and the electrised shot, through which rarefied air the electric fluid could more readily pass.

Referring to what Franklin had to say about the action of sunlight in this connection, Arthur Schuster, in hisSome Remarkable Passages in the Writings of Benjamin Franklin, observes: "Had Franklin used a clean piece of zinc instead of iron shot he might have anticipated Hertz's discovery of the action of strong light on the discharge of gases."

In the course of one of his experiments with an electrified can, Franklin reached the conclusion that a cork, which he had lowered into the can, was not attracted to its internal surface, as it would have been to its external, because the mutual repulsion of the two inner opposite sides of the can might prevent the accumulation of an electrical atmosphere upon them. From the same experiment, the genius of Henry Cavendish deduced his law that electrical repulsion varies inversely as the square of the distance between the charges.

Instead of declining, it can truly be said that the reputation of Franklin as an electrical investigator and writerhas increased with the progress of electrical science. "We shall, I am sure," remarks Professor J. J. Thomson in hisElectricity and Matter, "be struck by the similarity between some of the views which we are led to take by the results of the most recent researches, with those enunciated by Franklin in the very infancy of the subject." Nor should we omit a tribute of Dr. William Garnett, in hisHeroes of Science, in regard to the statements in Franklin's first letters to Collinson. "They are," he says, "perfectly consistent with the views held by Cavendish and by Clerk Maxwell, and, though the phraseology is not that of modern text-books, the statements themselves can hardly be improved upon to-day."

If Franklin achieved a higher degree of success in the electrical than in any other scientific field, it was partly, at any rate, because he never again had the opportunity to give such continuous attention to scientific pursuits. To him this was at times a source of very great disappointment. In one of his letters to Beccaria, dated Sept. 21, 1768, he tells the latter that, preoccupied as he was, he had constantly cherished the hope of returning home, where he could find leisure to resume the philosophical studies that he had shamefully put off from time to time. In a letter, some eleven years later, from Paris, to the same correspondent, he said that he was then prevented by similar distractions from pursuing those studies in which he always found the highest satisfaction, and that he was grown so old as hardly to hope for a return of the leisure and tranquillity, so necessary for philosophical disquisitions. To Sir Joseph Banks he was inspired some years later, by recent astronomical discoveries, made under the patronage of the Royal Society, to write: "I begin to be almost sorry I was born so soon, since I cannot have the happiness of knowing what will be known 100 years hence," Indeed, to him, leisure, whether only the seclusion of a thirty-day voyage across the Atlantic, orthe final cessation of public life, was but another term for recurrence to his scientific predilections. When he received his leave from Congress to return home from Paris, he wrote joyously to Ingenhousz: "I shall now be free of Politicks for the Rest of my Life. Welcome again my dear Philosophical Amusements." There was, to use his own expression, still too much flesh on his bones for his countrymen to allow him any time except for political experiments; but, for proof of the eager interest that he felt in science, and of the prominent position, that he occupied in the scientific world of America, until the last, we need go no further than the fact that, when he died, the meetings of the American Philosophical Society had, for some time, been held at his home in Philadelphia.

How far Franklin might have added to his reputation as a man of science, if he had not become engrossed by political duties and cares, is mere matter of surmise. But there can be no doubt that he was eminently fitted in many respects for scientific inquiry. The scientific temperament he possessed in the very highest degree. He loved the truth too much to allow the workings of human weakness in himself or others to deface its fair features. In reporting to Collinson the electrical achievements, which crowned him with such just renown, he almost invariably spoke of them as if they were the joint achievements of a group of collaborators, of whom he was but one. The generous alacrity, with which he credits to his friends Hopkinson, Kinnersley, or Syng exclusively special discoveries or inventions, made by them, shows conclusively enough how little this was true. There is no reason to believe that his letters to Collinson on electricity would ever have been published but for the unsolicited initiative of Dr. Fothergill and Collinson; or that they would ever have been translated into French but for the spontaneous persuasion that Buffon brought to bear upon D'Alibard. In a letter to Collinson, after expressing distrust of anhypothesis, advanced by him in former letters to the same correspondent, he declares that he is ashamed to have expressed himself in so positive a manner. Indeed, he said, he must request Collinson not to expose those letters, or, if he communicated them to any of his friends, at least to conceal the name of the author. His attitude towards his scientific triumphs was, when not that of entire self-effacement, always that of unaffected humility.

I am indebted for your preceding letter [he wrote in his forty-seventh year to John Perkins] but business sometimes obliges one to postpone philosophical amusements. Whatever I have wrote of that kind, are really, as they are entitled, butConjecturesandSuppositions; which ought always to give place, when careful observation militates against them. I own I have too strong a penchant to the building of hypotheses; they indulge my natural indolence: I wish I had more of your patience and accuracy in making observations, on which, alone, true philosophy can be founded.

Equally candid and noble are other observations in a subsequent letter to the same correspondent. Referring to certain objections, made by Perkins to his theory of water spouts, he observed:

Nothing certainly can be more improving to a Searcher into Nature, than Objections judiciously made to his Opinions, taken up perhaps too hastily: For such Objections oblige him to re-study the Point, consider every Circumstance carefully, compare Facts, make Experiments, weigh Arguments, and be slow in drawing Conclusions. And hence a sure Advantage results; for he either confirms a Truth, before too lightly supported; or discovers an Error, and receives Instruction from the Objector.In this View I consider the Objections and Remarks you sent me, and thank you for them sincerely.

In this View I consider the Objections and Remarks you sent me, and thank you for them sincerely.

When he found that he was in error, it cost him no struggle to recant. For a while he believed the sea to bethe grand source of lightning, and built up an imposing fabric of conclusions upon the belief; but he did not hesitate afterwards to admit that he had embraced this opinion too hastily. The same thing is true of the opinion that he held for a time, that the progress of a ship westward, across the Atlantic, is retarded by the diurnal motion of the earth. He supposed that the melting brought about by the action of lightning was a cold fusion until holes burnt in a floor by portions of a molten bell wire convinced him that this was not so.

I was too easily led into that error [he said] by accounts given even in philosophical books, and from remote ages downwards, of melting money in purses, swords in scabbards, etc. without burning the inflammable matters that were so near those melted metals. But men are, in general, such careless observers, that a philosopher can not be too much on his guard in crediting their relations of things extraordinary, and should never build an hypothesis on anything but clear facts and experiments, or it will be in danger of soon falling, as this does, like a house of cards.

In one of his letters to Collinson, he declared that, even though future discoveries should prove that certain conjectures of his were not wholly right, yet they ought in the meantime to be of some use by stirring up the curious to make more experiments and occasion more exact disquisitions. Following out the same thought in another letter to Collinson he concluded: "You are at liberty to communicate this paper to whom you please; it being of more importance that knowledge should increase, than that your friend should be thought an accurate philosopher." In a letter to John Lining, in which he described the experiment from which Cavendish deduced the law of which we have spoken, he observed:

I find a frank acknowledgement of one's ignorance is not only the easiest way to get rid of a dificulty, but the likeliestway to obtain information, and therefore I practise it: I think it an honest policy. Those who affect to be thought to know everything, and so undertake to explain everything often remain long ignorant of many things that others could and would instruct them in, if they appeared less conceited.

The fact is that Franklin had such a keen sense of the dignity and invincibility of truth that he could not be induced to enter into any personal controversy about it. His feelings with regard to such controversies are pointedly expressed in theAutobiographyin connection with the attack made by the Abbé Nollet upon his electrical experiments.

I once purpos'd [he said] answering the abbé, and actually began the answer; but, on consideration that my writings contain'd a description of experiments which anyone might repeat and verify, and if not to be verifi'd, could not be defended; or of observations offer'd as conjectures, and not delivered dogmatically, therefore not laying me under any obligation to defend them; and reflecting that a dispute between two persons, writing in different languages, might be lengthened greatly by mistranslations, and thence misconceptions of one another's meaning, much of one of the abbé's letters being founded on an error in the translation, I concluded to let my papers shift for themselves, believing it was better to spend what time I could spare from public business in making new experiments, than in disputing about those already made.

But in this instance, too, after all, he acted upon the principle, stated in one of his letters to Cadwallader Colden, that he who removes a prejudice, or an error from our minds contributes to their beauty, as he would do to that of our faces who should clear them of a wart or a wen. He went through his experiments again, and satisfied himself that the Abbé had not shaken his positions. At one time, when he was hesitating as to whether he shouldreply to him, he heard that D'Alibard was preparing to do so. "Perhaps," he wrote to his friend, James Bowdoin, "it may then appear unnecessary for me to do anything farther in it. And will not one's vanity be more gratified in seeing one's adversary confuted by a disciple, than even by one's self?" When Wilson published a pamphlet, contending that lightning rods should be blunt rather than pointed, he simply observed, "I have not answered it, being averse to Disputes."

Not only his temperament but his general mental attitude was instinctively scientific. As we have seen, while Whitefield's other auditors were standing mute and spellbound, he was carefully computing the distance that the words of the orator would carry. As we have also seen, when his soldiers were cutting down the giant pines at Gnadenhutten, he had his watch out, deep in his observation of the time that it took them to fell a tree. When his friend, Small, complained of deafness, he wrote to him that he had found by an experiment at midnight that, by putting his thumb and fingers behind his ear, and pressing it out and enlarging it as it were with the hollow of his hand, he could hear the tick of a watch at the distance of forty-five feet which was barely audible at a distance of twenty feet without these aids. Even in his relations to the simplest concerns of life, he had always the eye of a man of science to weight, measure, dimension and distance. If anyone wishes to see how easily he reduced everything to its scientific principles, let him read Franklin's letter to Oliver Neave, who thought that it was too late in life for him to learn to swim. With the confidence bred by a proper sense of the specific gravity of the human body as compared with that of water, Franklin said, there was no reason why a human being should not swim at the first trial. If Neave would only wade out into a body of water, until it came up to his breast and by a cast of his hand sink an egg to the bottom, between him and the shore, where itwould be visible, but could not be reached except by diving, and then endeavor to recover it, he would be surprised to find what a buoyant thing water was.

Franklin also had all the inquisitiveness of a born philosopher. The winds, the birds, the fish, the celestial phenomena brought to his attention on his first voyage from England, the sluggish movement of his ship on his voyage to England in 1757, the temperature and movement of the Gulf Stream, the social and religious characteristics of the Moravians, Indian traits and habits, the still flies in their bath of Madeira wine—all excited his insatiable curiosity, and started him off on interesting trains of observation or reflection.

He was in the 78th year of his age, when, in the sight of fifty thousand people, one of the balloons recently invented by the Montgolfiers, and inflated with gas, produced by pouring oil of vitriol on iron filings, ascended from the Champs de Mars, shining brightly in the sun during the first stages of its ascent, then dwindling until it appeared scarcely larger than an orange, and then melting away in the clouds that had never before been invaded by such a visitant. But so fresh still was his interest in every triumph of human ingenuity, that it required a long letter to Sir Joseph Banks, the President of the Royal Society, supplemented by two postscripts, to disburthen his mind of the sensations and thoughts excited by the thrilling spectacle. Mingled in this letter with many precise details of size, weight and distance are the speculations of the Parisians with respect to the practical uses to which the toy might be put. Some believed that, now that men might be supported in the air, nothing was wanted but some light handy instruments to give and direct motion. Others believed that a running footman, or a horse, slung and suspended under such a globe, so as to diminish the weight of their feet on the ground to perhaps eight or ten pounds, might, with a fair wind, run in astraight line across country as fast as that wind, and over hedges, ditches and even waters. Still other fantasies were that in time such globes might be kept anchored in the air for the purpose of preserving game, or converting water into ice; or might be turned to pecuniary profit as a means of giving recreation-seekers a chance, at an altitude of a mile, to see far below them a vast stretch of the terrestrial surface. Already, said Franklin, one philosopher, M. Pilâtre de Rozier, had applied to the Academy for the privilege of ascending in a larger Montgolfier in order to make certain scientific experiments. The peasants at Gonesse, however, who had seen the balloon, cut adrift on the Champs de Mars, fall to the earth, had regarded it with very different feelings from the citizens of Paris. Frightened, and conceiving from its bounding a little, when it touched the ground, that there was some living animal in it, they had attacked it with stones and knives, so that it was much mangled.

With a subsequent letter to Dr. Price, Franklin enclosed a small balloon, which his grandson had filled with inflammable air the night before, and which, after mounting to the ceiling of Franklin's chamber, had remained rolling about there for some time. "If a Man," this letter suggestively asks, "should go up with one of the large ones, might there not be some mechanical Contrivance to compress the Globe at pleasure; and thereby incline it to descend, and let it expand when he inclines to rise again?" The same eager curiosity about the balloon was manifested by Franklin in many other later letters. Another great one, he informed Banks, had gone up from Versailles. It was supposed to have been inflated with air, heated by burning straw, and to have risen about two hundred toises; but did not continue long at that height, and, after being wafted in a horizontal direction by the wind, descended gently, as the air in it grew cooler. "So vast a Bulk," said Franklin, "when it began to rise somajestically in the Air, struck the Spectators with Surprise and Admiration. The Basket contain'd a Sheep, a Duck & a Cock, who except the Cock receiv'd no hurt by the fall." Another balloon of about five feet in diameter, the same letter stated, had been sent up about one o'clock in the morning with a large lanthorn under it by the Duke de Crillon at an entertainment, given by him, during the preceding week, in the Bois de Boulogne in honor of the birth of two Spanish princes. These were but a few of many recent ascensions. Most interesting of all, however, a new balloon, designed by Messieurs Charles and Robert, who were men of science and mechanical dexterity, was to carry up a man.

Another balloon, described by Franklin in one of his letters to Banks, was open at the bottom, and was fed with heated air from a grate, fixed in the middle of the opening, which was kept replenished with faggots and sheaves of straw by men, posted in a wicker gallery, attached to the outside of the lower part of the structure. By regulating the amount of fire in the grate, the balloon could be given an upward or downward direction at pleasure.

It was thought, Franklin said, that a balloon of this type, because of the rapidity and small expense, with which it could be inflated, might be made useful for military purposes.

Still another balloon described by Franklin in the same letter was one which was to be first filled with "permanently elastic inflammable air," and then closed. It was twenty-six feet in diameter, and made of gores of red and white silk, which presented a beautiful appearance. There was a very handsome triumphal car, to be suspended from it, in which two brothers, the Messrs. Robert, were to ascend with a table for convenience in jotting down their thermometric and other observations. There was no telling, Franklin declared, how far aeronautic improvementsmight be pushed. A few months before, the idea of witches riding through the air on a broomstick, and that of philosophers upon a bag of smoke would have appeared equally impossible and ridiculous. The machines, however, he believed, would always be subject to be driven by the winds, though perhaps mechanic art might find easy means of giving them progressive motion in a calm, and of slanting them a little in the wind. English philosophy was too bashful, and should be more emulous in this field of competition. If, in France, they did a foolish thing, they were the first to laugh at it themselves, and were almost as much pleased with abon motor a goodchanson, that ridiculed well the disappointment of the project, as they might have been with its success.

The experiment might be attended with important consequences that no one could foresee.

Beings of a frank and—nature far superior to ours [the letter continued] have not disdained to amuse themselves with making and launching balloons, otherwise we should never have enjoyed the light of those glorious objects that rule our day and night, nor have had the pleasure of riding round the sun ourselves upon the balloon we now inhabit.

In due course, the Messrs. Robert, accompanied by M. Charles, a professor of experimental philosophy, and an enthusiastic student of aeronautics, made their perilous venture, which was likewise fully chronicled by Franklin. The spectators, he said, were infinite, crowding about the Tuileries, on the quays and bridges, in the fields and streets, and at the windows, and on the roofs, of houses. The device of stimulating flagging ascent by dropping sand bags from the car was one of the features of this incident, and so was the device of protecting the envelope of the balloon from rupture by covering it with a net, as well as that of lowering it by letting a part of its contents escape through a valve controlled by a cord.

Between one and two o'clock [Franklin's narrative states] all eyes were gratified with seeing it rise majestically from among the trees, and ascend gradually above the buildings, a most beautiful spectacle. When it was about two hundred feet high, the brave adventurers held out and waved a little white pennant, on both sides their car, to salute the spectators who returned loud claps of applause.

When Franklin last saw the vanishing form of this balloon, it appeared no bigger than a walnut. The experiment proved a most prosperous one. From first to last the aerial navigators retained perfect command of their air-ship, descending, when they pleased, by letting some of the air in it escape, and rising, when they pleased, by discharging sand; and at one time skimming over a field so low as to be able to talk to some laborers. Pleased as Franklin was with the experiment, he wrote to Henry Laurens that he yet feared that the machine would hardly become a common carriage in his time, though, being the easiest of allvoitures, it would be extremely convenient to him, now that his malady forbade him the use of the old ones over a pavement. The idea, however, was such an agreeable one to him that, when he returned to Philadelphia, he wrote to his friend Jean Baptiste Le Roy that he sometimes wished that he had brought a balloon from France with him sufficiently large to raise him from the ground, and to permit him, without discomfort from his stone, to be led around in his novel conveyance by a string, attached to it, and held by an attendant on foot.

On the whole, it appeared to Franklin that the invention of the balloon was a thing of great importance.

Convincing sovereigns of the Folly of Wars [he wrote to Ingenhousz] may perhaps be one Effect of it; since it will be impracticable for the most potent of them to guard his Dominions. Five thousand Balloons, capable of raising two Men each could not cost more than Five Ships of the Line; andwhere is the Prince who can afford so to cover his Country with Troops for its Defence, as that Ten Thousand Men descending from the Clouds might not in many places do an infinite deal of mischief, before a Force could be brought together to repel them?

But nothing happened in Franklin's time, nor has happened since, to warrant the belief that human flying-devices of any sort will ever be free enough from danger to human life to be a really useful vehicle of transportation in times of peace. So far their principal value has been during war, when human safety has little to choose between the earth and the sky, but it is fair to say that Franklin would have loathed war even more deeply than he did, if he could have lived to see them in the form of aeroplane or dirigible, making their way through the air like winged monsters of the antediluvian past, and dropping devilish agencies of death and desolation upon helpless innocence, and the fairest monuments of human industry and art. Poor M. Pilâtre de Rozier, whom we have already mentioned, and who was no less a person than the Professor of Chemistry, at the Athenée Royale, of which he was the founder, fell with a companion, from an altitude of one thousand toises to the rocky coast near Boulogne-sur-Mer, and was, as well as his companion, dashed to pieces. Since his time the discharioted Phaetons, who have fallen from the upper levels of the atmosphere, even when not engaged in war, with the same fearful result, have been numerous enough to constitute a ghastly necrology. Nor, it would appear, was the peril under the conditions of aerial navigation in its earliest stages limited to the aeronaut himself. In dissuading Ingenhousz from attempting a balloon experiment, Franklin said that it was a serious thing to draw out from their affairs all the inhabitants of a great city and its environs, and that a disappointment made them angry. At Bordeaux lately, a person, who pretended to send up a balloon, and had receivedmoney from many people, not being able to make it rise, the populace were so exasperated that they pulled down his house, and had like to have killed him. Anyone, who has ever heard the execrations hurled at the head of a baseball umpire in the United States, when one of his decisions has failed to command general assent, will experience no difficulty, we are sure, in understanding the force of the impulse that provoked this outbreak of Gallic excitement.

The enthusiasm, aroused in Franklin by the balloon, is not more noticeable than his brooding desire to find some practical use for it. The visionary speculation, which seeks to take the moon in its teeth, was no part of his character. He grew no orchids in the air. To use his homely words in a letter to Charles Thomson, he made no shoes for feet that he had never measured. Every conclusion, every hypothesis had to be built upon a basis of patient observation and gradual induction; every invention or discovery had to have some useful application.

At an earlier period than that of the discovery of the balloon, his inquisitive spirit had led him to the study of marsh-gas and the pacifying effect of oil upon troubled waters. In 1764, he had reason to believe that a friend of his had succeeded in igniting the surface of a river in New Jersey, after stirring up the mud beneath it, but his scientific friends in England found it difficult to believe that he had not been imposed upon; and the Royal Society withheld from publication among its Transactions a paper on the experiment, written by Dr. Finley, the President of Princeton College, and read before it. Franklin twice tried it in England without success, and he prosecuted his investigation with such energy and persistency that he finally contracted an intermittent fever by bending over the stagnant water of a deep ditch, and inhaling its foul breath, or, as would now be said, by being bitten by a mosquito hovering about it.

In 1757, when on one of the ships, bound on Lord Loudon's fool's errand to Louisburg, he observed that the water in the wake of two of them was remarkably smooth, while that in the wake of the others was ruffled by the wind, which was blowing freshly, and, when he spoke of the circumstance to his captain, the latter answered somewhat contemptuously, as if to a person ignorant of what everybody else knew, "The cooks have, I suppose, been just emptying their greasy water through the scuppers, which has greased the sides of those ships a little." The incident, and what he had read in Pliny about the practice among the seamen of Pliny's time of calming rough seas with oil, made him resolve to test the matter by experiment at the first opportunity. This intention was afterwards strengthened, when he was again at sea in 1762, by the "wonderful quietness" of oil, resting on the surface of an agitated bed of water in the glass lamp swinging in his cabin, and by the supposition of an old sea captain that the phenomenon was in keeping with the practice, pursued by the Bermudians, of putting oil on water, when they would strike fish. By the same captain, he was told that he had heard that fishermen at Lisbon were in the habit of emptying a bottle or two of oil on the sea, when the breakers on the bar at that port were running too high for their boats to cross it in safety. From another person, he learnt that, when divers in the Mediterranean needed more light for their business, they spewed out from their mouths now and then a small quantity of oil, which, rising to the surface, smoothed out its refracting waves. This additional information supplied his curiosity with still further fuel. It all ended in his dropping a little oil from a cruet on a large pond at Clapham. The fluid spread with surprising swiftness over the surface, on which it had fallen; but he found that he had made the mistake of dropping it on the leeward, instead of the windward, side of the pond. When this mistake wasrepaired, and a teaspoonful of oil was poured on its windward side, where the waves were in an incipient state, and the oil could not be driven back on the shore, an instant calmness diffused itself over a space several yards square, which extended gradually until it reached the lee side of the pond, making all that quarter of it, perhaps half an acre, as smooth as a looking-glass. After this, he took with him, whenever he went into the country, a little oil, in the upper hollow joint of his bamboo cane for the purpose of repeating his experiment, whenever he had a chance to do so, and, when he did repeat it, it was usually with success.

Far from being so successful, however, was the experiment when, on a blustering, unpleasant day, he attempted, with the co-operation of Sir Joseph Banks and other friends, to still the surf on a shore at Portsmouth with oil poured continually on the sea, at some distance away, through a hole, somewhat bigger than a goose quill, in the cork of a large stone bottle, though the effusion did flatten out a considerable tract of the sea to such an extent that a wherry, making for Portsmouth, seemed to turn into that tract of choice, and to use it from end to end as a piece of turnpike road. All this is described by Franklin in a letter to William Brownrigg, dated November 7, 1773, in which he cited some other illustrations of the allaying effect of oil on waves besides those that we have mentioned, and developed the philosophy of the subject with that incomparable clarity of his, not unlike the action of oil itself in subduing refractions of light.

Now I imagine [he says] that the wind, blowing over water thus covered with a film of oil, can not easilycatchupon it, so as to raise the first wrinkles, but slides over it, and leaves it smooth as it finds it. It moves a little the oil indeed, which being between it and the water, serves it to slide with, and prevents friction, as oil does between those parts of a machinethat would otherwise rub hard together. Hence the oil dropped on the windward side of a pond proceeds gradually to leeward, as may be seen by the smoothness it carries with it, quite to the opposite side. For the wind being thus prevented from raising the first wrinkles, that I call the elements of waves, cannot produce waves, which are to be made by continually acting upon, and enlarging those elements, and thus the whole pond is calmed.

And the water in which the Bermudian struck his fish is not more limpid than these observations suggested by the Portsmouth experiment:

I conceive, that the operation of oil on water is, first, to prevent the raising of new waves by the wind; and, secondly, to prevent its pushing those before raised with such force, and consequently their continuance of the same repeated height, as they would have done, if their surface were not oiled. But oil will not prevent waves being raised by another power, by a stone, for instance, falling into a still pool; for they then rise by the mechanical impulse of the stone, which the greasiness on the surrounding water cannot lessen or prevent, as it can prevent the winds catching the surface and raising it into waves. Now waves once raised, whether by the wind or any other power, have the same mechanical operation, by which they continue to rise and fall, as apendulumwill continue to swing a long time after the force ceases to act by which the motion was first produced; that motion will, however, cease in time; but time is necessary. Therefore, though oil spread on an agitated sea may weaken the push of the wind on those waves whose surfaces are covered by it, and so, by receiving less fresh impulse, they may gradually subside; yet a considerable time, or a distance through which they will take time to move, may be necessary to make the effect sensible on any shore in a diminution of the surf; for we know, that, when wind ceases suddenly, the waves it has raised do not as suddenly subside, but settle gradually, and are not quite down till after the wind has ceased. So, though we should, by oiling them, take off the effect of wind on waves already raised, it is not to beexpected that those waves should be instantly levelled. The motion they have received will, for some time, continue; and, if the shore is not far distant, they arrive there so soon, that their effect upon it will not be visibly diminished.

Nor was it on Clapham Pond and at Portsmouth alone that Franklin, when in England, tested the tranquillizing properties of oil. He performed the same experiment on Derwentwater and a small pond near the house of John Smeaton, the celebrated engineer, at Austhorpe Lodge; and also on a large sheet of water at the head of the Green Park. And the idea that there was something almost supernatural about his quick insight and fertility of conception, of which we find more than one trace in the utterances of his contemporaries, is suggested in an interesting manner in the account left to us by the Abbé Morellet of one of these experiments, which he witnessed when Colonel Barre, Dr. Hawkesworth, David Garrick, Franklin and himself happened to be guests of Lord Shelburne at Wycombe in 1772.

It is true [the Abbé says] it was not upon the waves of the sea but upon those of a little stream which flowed through the park at Wycombe. A fresh breeze was ruffling the water. Franklin ascended a couple of hundred paces from the place where we stood, and simulating the grimaces of a sorcerer, he shook three times upon the stream a cane which he carried in his hand. Directly the waves diminished and soon the surface was smooth as a mirror.

On one occasion, William Small wrote to him from Birmingham that Matthew Boulton had "astonished the rural philosophers exceedingly by calming the wavesà la Franklin."

Struck, when travelling on a canal in Holland, with the statement of a boatman that their boat was going slow because the season had been a dry one, and the water in the canal was not as deep as usual, Franklin, by experimentwith a trough and a little boat borrowed for the purpose, established the fact that the friction caused by the displacement by a moving boat of shallow water is measurably greater than that caused by the displacement by such a boat of deeper water. Under like conditions in other respects, the difference, he concluded, in a distance of four leagues, was the difference between five and four hours.

A conversation with Captain Folger, of Nantucket, produced far more important consequences. Influenced by what the captain told him of the knowledge that the Nantucket whalers had acquired of the retarding effect of the Gulf Stream upon navigation, Franklin induced him to plat for him the dimensions, course and swiftness of the stream, and to give him written directions as to how ships, bound from the Newfoundland Banks to New York, might avoid it, and at the same time keep clear of certain dangerous banks and shoals. The immediate object of Franklin was to procure information for the English Post Office that would enable the mail packets between England and America to shorten their voyages. At his instance, Captain Folger's drawing was engraved on the old chart of the Atlantic at Mount and Page's, Tower Hill, and copies of it were distributed among the captains of the Falmouth packets. Ever afterwards the Gulf Stream was a favorite field of investigation to him, when at sea, and its phenomena were mastered by him with remarkable thoroughness. It was generated, he conjectured, by the great accumulation of water on the eastern coast of America created by the trade winds which constantly blew there. He found that it was always warmer than the sea on each side of it, and that it did not sparkle at night; and he assigned to its influence the tornadoes, waterspouts and fogs by which its flow was attended.

Franklin also possessed to a striking degree the inventive capacity which is such a valuable qualification for experimental philosophy. We have already seen howready his mechanical skill was in supplying printing deficiencies. Speaking of the pulse glasses, made by Nairne, in which water could be brought to the boiling point with the heat of the hand, he tells us:

I plac'd one of his glasses, with the elevated end against this hole (a hole that he had opened through the wainscot in the seat of his window for the access of outside air); and the bubbles from the other end, which was in a warmer situation, were continually passing day and night, to the no small surprize of even philosophical spectators.

As he sat in his library at Philadelphia, in his last years, he was surrounded by various objects conceived by his own ingenuity. The seat of his chair became a step-ladder, when reversed, and to its arm was fastened a fan that he could work with a slight motion of his foot. Against his bookcase rested "the long arm" with which he lifted down the books on its upper shelves. The hours, minutes and seconds were told for him by a clock, of his own invention, with only three wheels and two pinions, in which even James Ferguson, mathematician as he was, had to confess that he experienced difficulty in making improvements. The very bifocal glasses, now in such general use, that he wore were a triumph of his own quick wit. Describing this invention of his in a letter to George Whatley, he said:

I therefore had formerly two Pair of Spectacles, which I shifted occasionally, as in travelling I sometimes read, and often wanted to regard the Prospects. Finding this Change troublesome, and not always sufficiently ready, I had the Glasses cut, and half of each kind associated in the same Circle.... By this means, as I wear my Spectacles constantly, I have only to move my Eyes up or down, as I want to see distinctly far or near, the proper Glasses being always ready. This I find more particularly convenient since my being in France, the Glasses that serve me best at Table to see what I eat, not being the best to see the Faces of those on the other Sideof the Table who speak to me; and when one's Ears are not well accustomed to the Sounds of a Language, a Sight of the Movements in the Features of him that speaks helps to explain; so that I understand French better by the help of my Spectacles.

The shrinking that a mahogany box, given to him in England, underwent, when subjected to the atmospheric conditions of America, suggested a hygrometer to him which Nairne afterwards constructed in accordance with his plans.[55]

His mind seems to have had no torpid moments, except, perhaps, when some Congressional orator was speaking. When, in early life, he had nothing else better to do, he would address himself to making magic squares and circles as intricate as Rosamond's walk. "He took it into his head," James Logan wrote to Collinson, "to thinkofmagical squares, in which he outdid Frenicle himself, who published above eighty pages in folio on that subject alone." Not willing to be outdone even by Stifelius, Franklin drew a square of such extraordinary numerical properties that not only did the numbers on all the rows and diagonals on its face total 2056, but the sum of the numbers on every group of 16 smaller squares on its face, when revealed through a hole in a piece of paper, moved backwards and forwards over its face, equalled precisely 2056 too. He likewise drew a

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