Abbildungen der Seite
PDF
EPUB

ing a knowledge of Franklin's principles in France. The King, Louis the Fifteenth, 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, Dalibard, and De Lor, an earnest desire of ascertaining the truth of his theory of thunder-gusts. Buffon erected his apparatus on the tower of Montbar, M. Dalibard at Marly-la-ville, and De Lor at his house in the Estrapade at Paris, some of the highest ground in that capital. Dalibard's machine first showed signs of electricity. On the 10th of May, 1752, a thunder-cloud passed over it in the absence of M. Dalibard, and a number of sparks were drawn from it by Coiffier, joiner, with whom Dalibard had left directions how to proceed, and by M. Raulet, the prior of Marlyla-ville.

“ An account of this experiment was given to the Royal Academy of Sciences, by M. Dalibard, in a Memoir dated May 13th, 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; amongst 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 ardor for discovery. Professor Richmann 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 Philadel. phia, 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 incontestably due to Franklin. Dalibard, who made the first experiments in France, says, that he only followed the track which Franklin had pointed out.

“ It has been of late asserted, that the honor 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 Presidéal of Nérac; 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 19th, 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 experiments, 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 diminished its natural quantity, or charged negatively. These experiments and observations opened a new field for investigation, upon which electricians enVOL. V.

12

tered with avidity; and their labors 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, but feebly supported, while the first philosophers in Europe stepped forth in defence of Franklin's principles, amongst whom Dalibard and Beccaria were the most distinguished. The opposition has gradually ceased, and the Franklinian system is now universally adopted, where science flourishes."

In speaking of the first publication of his papers on electricity, Franklin himself says; “Obliged as we were to Mr. Collinson for the present of the tube, &c., I thought it right he should be informed of our success in using it, and wrote him several letters containing accounts of our experiments. He got them read in the Royal Society, where they were not at first thought worth so much notice as to be printed in their Transactions. One paper, which I wrote for Mr. Kinnersley, on the sameness of lightning with electricity, I sent to Mr. Mitchel, an acquaintance of mine, and one of the members also of that Society; who wrote me word, that it had been read, but was laughed at by the connoisseurs. The papers, however, being shown to Dr. Fothergill, he thought them of too much value to be stifled, and advised the printing of them. Mr. Collinson then gave them to Cave for publication, in his Gentleman's Magazine; but he chose to print them separately in a pamphlet, and Dr. Fothergill wrote the preface. Cave, it seems, judged rightly for his profession; for, by the additions that arrived afterwards, they swelled to a quarto volume, which has had five editions, and cost him nothing for copy-money."

The following is an extract from the Preface to the first edition of the pamphlet published by Cave, as above mentioned.

“It may be necessary to acquaint the reader, that the following observations and experiments were not drawn up with a view to their being made public, but were communicated at different times, and most of them in letters, written on various topics, as matters only of private amusement.

“But some persons, to whom they were read, and who had themselves been conversant in electrical disquisitions, were of opinion, they contained so many curious and interesting particulars relative to this affair, that it would be doing a kind of injustice to the public, to confine them solely to the limits of a private acquaintance.

“The editor was therefore prevailed upon to commit such extracts of letters and other detached pieces as were in his hands to the press, without waiting for the ingenious author's permission so to do; and this was done with the less hesitation, as it was apprehended the author's engagements in other affairs would scarce af. ford him leisure to give the public his reflections and experiments on the subject, finished with that care and precision, of which the treatise before us shows he is alike studious and capable."

Dr. Priestley, in his History of Electricity, published in the year 1767, gives a full account of Franklin's experiments and discoveries.

“Nothing was ever written upon the subject of electricity," he says, “ which was more generally read and admired in all parts of Europe, than these letters. There is hardly any European language into which they have not been translated; and, as if this were not sufficient to make them properly known, a translation of them has lately been made into Latin. It is not easy to say, whether we are most pleased with the simplicity and perspicuity with which these letters are written, the modesty with which the author proposes every hypothesis of his own, or the noble frankness with which he relates his mistakes, when they were corrected by subsequent experiments.

“Though the English have not been backward in acknowledging the great merit of this philosopher, he has had the singular good fortune to be, perhaps, even more celebrated abroad than at home; so that, to form a just idea of the great and deserved reputation of Dr. Franklin, we must read the foreign publications on the subject of electricity; in many of which the terms Franklinism, Franklinist, and the Franklinian system, occur in almost ever; page. In consequence of this, Dr. Franklin's principles bid fair to be handed down to posterity as equally expressive of the true principles of

In the year

electricity, as the Newtonian philosophy is of the true system of nature in general."

The observations and theories of Franklin met with high favor in France, where his experiments were repeated, and the results verified to the admiration of the scientific world. 1753, his friend, Peter Collinson, wrote to him from London; “ The King of France strictly commands the Abbé Mazéas to write a letter in the politest terms to the Royal Society, to return the King's thanks and compliments, in an express manner, to Mr. Franklin of Pennsylvania, for his useful discoveries in electricity, and the application of pointed rods to prevent the terrible effects of thunder-storms." And the same Mr. Collinson wrote as follows to the Reverend Jared Eliot, of Connecticut, in a letter dated, London, November 22d, 1753. “Our friend Franklin will be honored on St. Andrew's day, the 30th instant, the anniversary of the Royal Society, when the Right Honorable the Earl of Macclesfield will make an oration on Mr. Franklin's new discoveries in electricity, and, as a reward and encouragement, will bestow on him a gold medal.” This ceremony accordingly took place, and the medal was conferred,

The best translation of Franklin's papers on electricity is that in French by M. Dubourg, published at Paris in two elegant quarto volumes, in the year 1773. Several of his other philosophical writings, and some of his political pieces, are also included in these volumes, with valuable additions and remarks by the learned translator. Letters and other original papers were transmitted by Dr. Franklin to M. Dubourg, and appeared for the first time in his translation. EDITOR.

TO PETER COLLINSON.

Introductory Letter.

Philadelphia, 28 March, 1747. SIR, Your kind present of an electric tube, with directions for using it, has put several of us on making electrical experiments, in which we have observed some particular phenomena, that we look upon to be new. I shall

« ZurückWeiter »