He engaged in a course of electrical experiments with all the ardour and thirst for discovery which characterized the philosophers of that day. Of all the branches of experimental philosophy, electricity had been least explored. The attractive power of amber is mentioned by Theophrastus and Pliny, and from them by later naturalists. In the year 1600, Gilbert, an English physician, enlarged considerably the catalogue of substances which have the property of attracting light bodies. Boyle, Otto Guericke, a burgomaster of Magdeburg, celebrated as the inventor of the airpump, Dr. Wall, and Sir Isaac Newton, added some facts. Guericke first observed the repulsive power of electricity, and the light and noise produced by it. In 1709, Hawkesbec communicated some important observations and experiments to the world. For several years electricity was entirely neglected, until Mr. Grey applied himself to it, in 1728, with great assiduity. He and his friend Mr. Wheeler made a great variety of experiments; in which they demonstrated that electricity may be communicated from one body to another, even without being in contact, and in this way may be conducted to a great distance. Mr. Grey afterward found that, by suspending rods of iron by silk or hair lines, and bringing an excited tube under them, sparks might be drawn, and a light perceived at the extremities in the dark. M. du Faye, intendant of the French king's gardens, made a number of experiments, which added not a little to the science. He made the discovery of two kinds of electricity, which he called vitreous and resinous; the former produced by rubbing glass, the latter from excited sulphur, sealing-wax, &c. But this idea he afterward gave up as erroneous. Between the year 1739 and 1742, Desauguliers made a number of experiments, but added little of importance. He first used the terms conductors and electrics per se. In 1742, several ingenious Germans engaged in this subject; of these the principal were, Professor Boze, of Wittemberg, Professor Winkler, of Leipsic, Gordon, a Scotch Benedictine monk, professor of philosophy at Erfurt, and Dr. Ludolf, of Berlin. The result of their researches astonished the philosophers of Europe. Their apparatus was large, and by means of it they were enabled to collect large quantities of the electric fluid, and thus to produce phenomena which had been hitherto unobserved. They killed small birds, and set spirits on fire. Their experiments excited the curiosity of other philosophers. Collinson, about the year 1745, sent to the Library Company of Philadelphia an account of these experiments, together with a tube, and directions how to use it. Franklin, with some of his friends, immediately engaged in a course of experiments, the result of which is well known. He was enabled to make a number of important discoveries, and to propose theories to account for various phenomena; which have been universally adopted, and which bid fair to endure for ages. His observations he communicated in a series of letters, to his friend Collinson, the first of which is dated March 28, 1747. In these he shows the power of points in draining and throwing off the electrical matter, which had hitherto escaped the notice of electricians. He also made the grand discovery of a plus and minus, or of a positive and negative state of electricity. We give him the honour of this without hesitation, although the English have claimed it for their countryman, Dr. Watson. Watson's paper is dated January 21, 1748; Franklin's July 11, 1747; several months prior. Shortly after, Franklin, from his principles of the plus and minus state, explained, in a satisfactory manner, the phenomena of the Leyden vial, first observed by Mr. Cuneus, or by Professor Muschenbroeck, of Leyden, which had much perplexed philosophers. He showed clearly that the bottle, when charged, contained no more electricity than before, but that as much was taken from one side as was thrown on the other; and that, to discharge it, nothing was necessary but to produce a communication between the two sides by which the equilibrium might be restored, and that then no signs of electricity would remain. He afterward demonstrated, by experiments, that the electricity did not reside in the coating, as had been supposed, but in the pores of the glass itself. After a vial was charged, he removed the coating, and found that, upon applying a new coating, the shock might still be received. In the year 1749, he first suggested his idea of explaining the phenomena of thunder-gusts, and of the aurora borealis, upon electrical principles. He points out many particulars in which lightning and electricity agree: and he adduces many facts, and reasonings from facts, in support of his positions. In the same year he conceived the astonishingly bold and grand idea of ascertaining the truth of his doctrine by actually drawing down the lightning, by means of sharp-pointed iron rods raised into the region of the clouds. Even in this uncertain state, his passion to be useful to mankind displays itself in a powerful manner. Admitting the identity of electricity and lightning, and knowing the power of points in repelling bodies charged with electricity, and in conducting their fire silently and imperceptibly, he suggested the idea of securing houses, ships, &c., from being damaged by lightning, by erecting pointed rods, that should rise some feet above the most elevated part, and descend some feet into the ground or the water. The effect of these, he concluded, would be either to prevent a stroke by repelling the cloud beyond the striking distance, or by drawing off the electrical fire which it contained; or, if they could not effect this, they would at least conduct the electric matter to the earth, without injury to the building.
It was not until the summer of 1752 that he was enabled to complete his grand and unparalleled discovery by experiment. The plan which he had originally proposed was to erect on some high tower or other elevated place a sentry-box, from which should rise a pointed iron rod, insulated by being fixed in a cake of resin. Electrified clouds passing over this would, he conceived, impart to it a portion of their electricity, which would be rendered evident to the senses by sparks being emitted when a key, the knuckle, or other conductor was presented to it. Philadelphia at this time afforded no opportunity of trying an experiment of this kind. While Franklin was waiting for the erection of a spire, it occurred to him that he might have more ready access to the region of clouds by means of a common kite. He prepared one by fastening two cross sticks to a silk handkerchief, which would not suffer so much from the rain as paper. To the upright stick was affixed an iron point. The string was, as usual, of hemp, except the lower end, which was silk. Where the hempen string terminated a key was fastened. With this apparatus, on the appearance of a thunder-gust approaching, he went out into the commons, accompanied by his son, to whom alone he communicated his intentions, well knowing the ridicule which, too generally for the interest of science, awaits unsuccessful experiments in philosophy. He placed himself under a shade to avoid the rain; his kite was raised; a thunder-cloud passed over it; no sign of electricity appeared. He almost despaired of success, when, suddenly, he observed the loose fibres of his string to move towards an erect position. He now presented his knuckle to the key, and received a strong spark. How exquisite must his sensations have been at this moment! On this experiment depended the fate of his theory. If he succeeded, his name would rank high among those who had improved science; if he failed, he must inevitably be subjected to the derision of mankind, or, what is worse, their pity, as a well-meaning man, but a weak, silly projector. The anxiety with which he looked for the result of his experiment may be easily conceived. Doubts and despair had begun to prevail, when the fact was ascertained in so clear a manner, that even the most incredulous could no longer withhold their assent. Repeated sparks were drawn from the key, a vial was charged, a shock given, and all the experiments made which are usually performed with electricity.
About a month before this period, some ingenious Frenchman had completed the discovery in the manner originally proposed by Dr. Franklin. The letters which he sent to Mr. Collinson, it is said, were refused a place in the Transactions of the Royal Society of London. However this may be, Collinson published them in a separate volume, under the title of "New Experiments and Observations on Electricity, made at Philadelphia, in America." They were read with avidity, and soon translated into different languages. A very incorrect French translation fell into the hands of the celebrated Buffon, who, notwithstanding the disadvantages under which the work laboured, was much pleased with it, and repeated the experiments with success. He prevailed on his friend, M. D'Alibard, to give his countrymen a more correct translation of the works of the American electrician. This contributed much towards spreading a knowledge of Franklin's principles in France. The king, Louis XV., hearing of these experiments, expressed a wish to be a spectator of them. A course of experiments was given at the seat of the Duc D'Ayen, at St. Germain, by M. de Lor. The applauses which the king bestowed upon Franklin excited in Buffon, D'Alibard, and De Lor, an earnest desire of ascertaining the truth of his theory of thunder-gust. Buffon erected his apparatus on the tower of Monthar, M. D'Alibard at Mary-la-ville, and De Lor at his house in the Estrapade at Paris, some of the highest ground in that capital. D'Alibard's machine first showed signs of electricity. On the 10th of May, 1752, a thunder-cloud passed it, in the absence of M'Alibard, and a number of sparks were drawn from it by Coiffier, a joiner, with whom D'Alibard had left directions how to proceed, and by M. Raulet the prior of Mary-la-ville. An account of this experiment was given to the Royal Academy of Sciences, by M. D'Alibard, in a memoir, dated May 13, 1752. On the 18th of May, M. de Lor proved equally successful with the apparatus erected at his own house. These philosophers soon excited those of other parts of Europe to repeat the experiment, among whom none signalized themselves more than Father Beccaria, of Turin, to whose observations science is much indebted. Even the cold regions of Russia were penetrated by the ardour for discovery. Professor Richman bade fair to add much to the stock of knowledge on this subject, when an unfortunate flash from his conductor put a period to his existence. The friends of science will long remember with regret the amiable martyr to electricity.
By these experiments Franklin's theory was established in the most convincing manner. When the truth of it could no longer be doubted, envy and vanity endeavoured to detract from its merit. That an American, an inhabitant of the obscure city of Philadelphia, the name of which was hardly known, should be able to make discoveries and to frame theories which had escaped the notice of the enlightened philosophers of Europe, was too mortifying to be admitted. He must certainly have taken the idea from some one else. An American, a being of an inferior order, make discoveries! Impossible. It was said that the Abbé Nollet, 1748, had suggested the idea of the similarity of lightning and electricity in his Leçons de Physique. It is true that the abbé mentions the idea, but he throws it out as a bare conjecture, and proposes no mode of ascertaining the truth of it. He himself acknowledges that Franklin first entertained the bold thought of bringing lightning from the heavens, by means of pointed rods fixed in the air. The similarity of lightning and electricity is so strong, that we need not be surprised at notice being taken of it as soon as electrical phenomena became familiar. We find it mentioned by Dr. Wall and Mr. Grey, while the science was in its infancy. But the honor of forming a regular theory of thunder-gusts, of suggesting a mode of determining the truth of it by experiments, and of putting these experiments in practice, and thus establishing the theory upon a firm and solid basis, is incontestibly due to Franklin. D'Alibard, who made the first experiments in France, says that he only followed the tract which Franklin had pointed out.
It has been of late asserted, that the honour of completing the experiment with the electrical kite does not belong to Franklin. Some late English paragraphs have attributed it to some Frenchman, whose name they do not mention: and the Abbé Bertholon gives it to M. de Romas, assessor to the presideal of Nerac: the English paragraphs probably refer to the same person. But a very slight attention will convince us of the injustice of this procedure: Dr. Franklin's experiment was made in June, 1752, and his letter, giving an account of it, is dated October 19, 1752. M. de Romas made his first attempt on the 14th of May, 1753, but was not successful until the 7th of June, a year after Franklin had completed the discovery, and when it was known to all the philosophers in Europe.
Besides these great principles, Franklin's letters on electricity contain a number of facts and hints which have contributed greatly towards reducing this branch of knowledge to a science. His friend, Mr. Kinnersley, communicated to him a discovery of the different kinds of electricity, excited by rubbing glass and sulphur. This, we have said, was first observed by M. du Faye, but it was for many years neglected. The philosophers were disposed to account for the phenomena rather from a difference in the quantity of electricity collected, and even Du Faye himself seems at last to have adopted this doctrine. Franklin at first entertained the same idea; but, upon repeating the experiment, he perceived that Mr. Kinnersley was right; and that the vitreous and resinous electricity of Du Faye were nothing more than the positive and negative states which he had before observed; and that the glass globe charged positively, or increased the quantity of electricity on the prime conductor, while the globe of sulphur diminishes its natural quantity, or charged negatively. These experiments and observations opened a new field for investigation, upon which electricians entered with avidity, and their labours have added much to the stock of our knowledge.
In September, 1752, Franklin entered upon a course of experiments to determine the state of electricity in the clouds. From a number of experiments he formed this conclusion: "That the clouds of a thunder-gust are most commonly in a negative state of electricity, but sometimes in a positive state;" and from this it follows, as a necessary consequence, "that, for the most part, in thunder-strokes, it is the earth that strikes into the clouds, and not the clouds that strike into the earth." The letter containing these observations is dated in September, 1753; and yet the discovery of ascending thunder has been said to be of a modern date, and has been attributed to the Abbé Bertholon, who published his memoir on the subject in 1776.
Franklin's letters have been translated into most of the European languages and into Latin. In proportion as they have become known, his principles have been adopted. Some opposition was made to his theories, particularly by the Abbé Nollet, who was, however, feebly supported, while the first philosophers in Europe stepped forth in defence of Franklin's principles, among whom D'Alibard and Beccaria were the most distinguished. The opposition has gradually ceased, and the Franklinian system is now universally adopted where science flourishes.
The important practical use which Franklin made of his discoveries, the securing of houses from injury by lightning, has been already mentioned. Pointed conductors are now very common in America; but prejudice has hitherto prevented their general introduction into Europe, notwithstanding the most undoubted proofs of their utility have been given. But mankind can with difficulty be brought to lay aside established practices, or to adopt new ones. And perhaps we have more reason to be surprised that a practice, however rational, which was proposed about forty years ago, should in that time have been adopted in so many places, than that it has not universally prevailed. It is only by degrees that the great body of mankind can be led into new practices, however salutary their tendency. It is now nearly eighty years since inoculation was introduced into Europe and America; and it is so far from being general at present, that it will require one or two centuries to render it so.
The disputes between the proprietaries and the people of the province continued in full force, although a war was raging on the frontiers. Not even the sense of danger was sufficient to reconcile, for ever so short a time, their jarring interests. The Assembly still insisted upon the justice of taxing the proprietary estates; but the governors constantly refused their assent to this measure, without which no bill could pass into a law. Enraged at the obstinacy, and what they conceived to be the unjust proceedings of their opponents, the Assembly at length determined to apply to the mother country for relief. A petition was addressed to the king in council, stating the inconveniences under which the inhabitants laboured, from the attention of the proprietaries to their private interest, to the neglect of the general welfare of the community, and praying for redress. Franklin was appointed to present this address, as agent for the province of Pennsylvania, and departed from America in June, 1757. In conformity to the instructions which he had received from the legislature, he held a conference with the proprietaries who then resided in England, and endeavoured to prevail upon them to give up the long-contested point. Finding that they would hearken to no terms of accommodation, he laid his petition before the council. During this time Governor Denny assented to a law imposing a tax, in which no discrimination was made in favour of the estates of the Penn family. They, alarmed at this intelligence and Franklin's exertions, used their utmost endeavours to prevent the royal sanction being given to this law, which they represented as highly iniquitous, designed to throw the burden of supporting government upon them, and calculated to produce the most ruinous consequences to them and their posterity. The cause was amply discussed before the privy council. The Penns found here some strenuous advocates; nor were there wanting some who warmly espoused the side of the people. After some time spent in debate, a proposal was made that Franklin should solemnly engage that the assessment of the tax should be so made as that the proprietary estates should pay no more than a due proportion. This he agreed to perform, the Penn family withdrew their opposition, and tranquillity was thus once more restored to the province.