« ZurückWeiter »
which he justly deserves, and the high opinion which not only myself, but the whole Society, entertain of his uncommon skill and abilities, as well in other branches of knowledge, as in this whereof I have been speaking; for which reason I shall put a constraint upon myself, and forbear entering into that encomium, which I really think to be due to him.
“ The advances, however, which this gentleman and others had made towards laying open the nature of electricity, though very considerable in themselves, left room for carrying on these inquiries still further. To this work Mr. Franklin earnestly applied himself; and, as his diligence and ingenuity deserved, so they met with, uncommon success. For, though some others might have begun to entertain suspicions of an analogy between the effects of lightning and electricity, yet I take Mr. Franklin to be the first, who, among other curious discoveries, undertook to show from experiments, that the former owed its origin entirely to the latter; and who pointed out an easy method whereby any one might satisfy himself of the truth of the fact, which he had so advanced.
“ This method, which he had pointed out, was so much approved, and has been so successfully put into execution in many different places, that it remains no longer a matter of suspicion and doubt, but is clear and plain to a demonstration, that electricity alone is the cause of that tremendous appearance, whose effects prove frequently so fatal in many parts of this terraqueous globe. And it were greatly to be wished, that some effectual and practicable way could be found by Mr. Franklin, or others, to prevent, or at least to lessen, the mischiefs, which too often attend that terrible meteor.
“Mr. Franklin's book has for some time been in the hands of most who hear me, and large accounts, drawn up by foreigners (as well as by the learned gentleman before mentioned), of Mr. Franklin's numerous and curious experiments, have been laid before this Society, besides those which himself has more immediately caused to be communicated to us at various times. It would therefore be impertinent in me to trespass upon your patience by entering into a detail of particulars, which, I am satisfied, you are all well acquainted with
“ True it is, that several learned men, both at home and abroad, do not entirely agree with him in all the conclusions, which he thinks may be deduced from the experiments he has made. But far be it from me to pretend to decide these points, more especially in this place and at this time. That matter is yet in dispute ; and, if I am rightly informed, Mr. Franklin is now preparing to produce in support of his sentiments still farther experiments, some of which, he flatters himself, will appear more surprising than any that have already been communicated to the world.
“ Let it therefore suffice for the present to say, that even those persons, who happen to differ from him in opinion as to some points, universally acknowledge his great merit, and particularly the learned gentleman, whom I have more than once mentioned, is pleased to declare Mr. Franklin to be 'a very able and ingenious man,' and says, “that he has a head to conceive, and a hand to carry into execution, whatever he thinks may conduce to enlighten the subject matter of which he is treating ;' and, although that gentleman 'cannot agree with him in some of his opinions, yet he thinks scarce anybody better acquainted with the subject of electricity than Mr. Franklin.' These testimonials, therefore, given by so capable as well as unprejudiced judges, in his favor, and more especially that character of him, which I have just quoted, joined with that opinion, which every one who has read his books must entertain of him, will sufficiently justify your Council in having adjudged to Mr. Franklin the Copley medal for this year, as a mark of distinction due to his unquestionable merit.
“Many and very considerable advantages and improvements have, within the space of some years past, been made in several branches of natural knowledge ; but there is ample room still remaining for the inquisitive and able philosopher to employ his skill and labor. The Book of Nature is a very huge and comprehensive volume; and, notwithstanding no small part of it has been unfolded and exposed to our view by learned and ingenious men of this and many other countries, yet it still contains abundantly sufficient matter to 'exercisé our talents upon, and which justly ought to excite our curiosity, and encourage us to proceed with vigor in our endeavours to bring to light what is at present concealed from our eyes. We know that few things are of so occult and obstinate a nature, as not to yield to sagacity, and to be forced to lay open their most hidden properties to the diligent and inquisitive inquirer.
“In confidence whereof let us pursue, with unwearied application and assiduity, our researches into every branch of natural philosophy. Nor let us be discouraged from such pursuits by a mistaken notion, that any part of it is too inconsiderable to deserve our regard and attention; since who could have entertained any hopes, some years ago, that electricity was capable of furnishing matter for so great and important discoveries, as have lately been made in relation thereto, and which at this time afford us a promising prospect of much more and greater, if due pains are not wanting, on our part, to search after them?
" It is, therefore, to be hoped, that those gentlemen, who have applied their thoughts and studies to lay open the amazing properties of electricity, will not sit down contented with the progress that has already been made therein, but will rather be encouraged thereby to proceed diligently in the same work. And I flatter myself, that Mr. Franklin will consider this honorable present not only as a reward, in some measure, of the discoveries with which he has already favored the world in relation to this very powerful agent in nature, but also as a proper incitement to carry on still farther his inquiries into this truly deserving and important subject. Nor do in the least doubt, that our worthy brother, Mr. Peter Collinson, to whom (as Mr. Franklin resides in a remote country) I shall recommend the care of conveying this medal to him, will make use of all proper means to induce him to persevere in so laudable an undertaking."
. In the Minutes of the Council, December 19th, 1754, it is recorded, “ A letter from Benjamin Franklin, Esquire, to the President and Council of the Royal Society, dated Philadelphia, 29 May, 1754, returning his thanks for the honor they have done him in bestowing on him the gold medal for the year 1753, was read.”
Franklin was elected a Fellow of the Royal Society on the 29th of April, 1756. — EDITOR.
LETTER FROM JOHN BAPTIST BECCARIA TO BENJAMIN
Experiments in Electricity.
READ AT THE ROYAL SOCIETY, FEBRUARY 14TH, 1760.
Benjamino Franklin, viro de re electrica meritissimo, Joannes Bap
tista Beccaria ex Scholis Piis S. P. D. 1. Sospitem ex America Londinum te appulisse gaudeo, vir præclarissime. Offero tibi de motibus electricis, qualem experimentis excudi, hypothesin ; partior hanc in duas partes, quemadmodum ipsa postulare videtur motuum hujusmodi differentia ; ago parte prima de accessionibus, de discessionibus dico parte altera.
2. Et continuo universam de accessionibus pertractationem meam ita paucis comprehendo; “Quum ignis electricus copiosior in corpore altero vi expandendi se ad æqualitatem trajicit in alterum, partem interjecti aeris dimovet e loco pro majore sua copia majorem; fit inde, ut aer a tergo corporibus adjacens deficiente fulcro aeris intermedii ruat versus ipsum medium locum; ruit vero non circumeundo corpora, quæ via est longior, atque impedita abs igne profluente, sed ipsa trudendo a tergo; hac aeris trusione accedunt corpora inæqualiter electrica; dum accedunt, accelerantur, quia pro accessione majore copiosior ignis interfluit, copiosior intermedius aer disjicitur, augeturque adeo momentum aeris a tergo trudentis.”
3. Aerem disjici ab interfluente electrico igne, scintillæ experimento demonstratur, quæ excitatur in medio tubulo, hinc clauso hermetice, inde impedito abs liquore aliquo, ipsa enim, disjiciens liquorem, disjectum aerem testatur.
4. Neque vero interfluens ignis aeris intermedii disjecti fulcrum potest supplere, quo aer corporibus a tergo adjacens sustineatur ; is enim liberrime effluit, et effunditur per alterum corpus; quare, cum non fulciatur ipse, nec fulcri vices potest agere.
5. Experimento res confirmatur plane luculentissimo; vittam ex charta inaurata longam pollices octo, latam lineas quatuor, convolvo
circa sese, ut cylindrum solidum D efformet; hunc suspendo serico filo D, G, sub fornice vitri pneumatici I, H, K, per cujus verticem
H init virga metallica B, C, desinens in metallicam sphæram C; figo in lance 1, K, virgam metallicam L, E, simili sphæra ornatam; nempe sphera C et E sunt in eodem plano cum pendulo D, atque ab ipso distant ambæ æqualiter; tum nexa catena A, B, quæ pertinet ad machinam electricam, virgæ B, C, et consequenter immisso electrico igne in virgam B, C, observo; 1. ante subductum aerem chartaceum cylindrum D agitari vehementissimis vibrationibus inter duas sphæras E, C; 2. dum aer subducitur, minui eam agitationen plane pro copia subducti aeris ; 3. omni, quantus potest, aere subducto, cylindrum D vix nutare. His observatis aerem restituo par. ticulatim; atque pro aere admisso video vibrationes iterum augescere, et fieri, quemadmodum antea, vehementissimas; quæ dum contemplor singula, atque omnia simul comprehendo animo, intelligo magnitudinem motuum electricorum aeri, vel toti, vel residuo proportione respondere.
6. Quod leviora corpuscula, bracteolæ, et pulvisculi, motu adhuc satis sensili agitentur in rarefacto aere, id in causa fuit, cur censuerim a principio cum physicis aliis electricos motus actioni ignis electrici in aerem acceptos referri non debere; quod, re nunc accuratius collata, residuos videam in residuo aere motus non majorem habere ad primos motus, qui fiunt in toto aere atmospherico,