EULOGY ON ALEXANDER VOLTA. IZd 



By thus following:, iu the order of their dates, the developmeuts of 

 atmospheric electricity, I gradually reach the works with which Yolta 

 has euriched this important branch of meteorology. The object of these 

 "works was by turns the improvement of the methods of observation 

 and the minute examination of the diliereut circumstances under which 

 the electricity was developed, which pervaded all the regions of the air. 



When a new branch of science has been discovered the experimental- 

 ists devote themselves almost exclusively to the discovery of new phe- 

 nomena, reserving their numerical valuation for later times. In elec- 

 tricity, for example, several physicists made themselves in this way a 

 well-merited reputation. The Leyden jar, we may add, was conspicuous 

 in all the laboratories of Europe, but no one had yet invented a veritable 

 electrometer. The first instrument of this kind was made iu 1749, and 

 was the work of Darcy and Le Koy, two members of this academy. 

 Its want of sensibility in small charges prevented its being adopted. 



The electrometer suggested by Xollet (1752) appeared at first sight 

 simpler, more convenient, and especially as having infinitely greater sen- 

 sibility. It was to consist of two wires, which after being electrified 

 would open, like the two branches of a compass, from the eflect of 

 repulsion. The measure sought would thus be reduced to the observa 

 tion of an angle. 



Cavallo realized what Xollet had only suggested, (17S0.) Ilis wires 

 were of metal, and had at their extremities small balls of the pith of 

 elder. Yolta finally abolished the elder and substituted dry straws 

 at the end of the wires. This change might seem unimportant if it 

 were not explained that the new electrometer alone possessed the valu- 

 able and unexpected i)roperty of giving, betw^een and 30^, the angu- 

 lar motions of the two straws exactly proportional to the electrical 

 charges. 



Volta's letter to Lichtenberg, dated 178G, iu which he established by 

 numerous experiments the pr-operties of the straw electrometer, con- 

 tained interesting views, no traces of which are to be found iu more 

 recent works. They relate to the means of rendering these instruments 

 comparable in the measurement of the strongest charges, and to cer- 

 tain combinations of the electrometer and condenser. This letter can- 

 not be too highly recommended to young physicists. It will initiate 

 them into the very difficult art of investigating ; it will teach them to 

 mistrust first impressions and to constantly vary the form. of the appa- 

 ratus; if tempted by an impatient temper to abandon the slow but sure 

 and beaten track of observation for seductive chimerical ideas, they 

 may, perhaps, be arrested on this slippery ground by beholding a man 

 of genius undaunted by the most minute details. And, moreover, at a 

 time when, save in a IVw honorable cases, the publication of a book is a 

 I)uroly business oi)eration, when scientific treatises, especially, modeled 

 after the same pattern, do not differ from each other, except perhaps 

 by a few sliglit shades iu the comi)ilation, often imleed imperceptible, 



