164 MEMOIR OF PELTIER. 



for tins that we take from 25 to 30 disks, provided only tliat tlieir surffice be a 

 little expanded, say from one to two square decimeters. Such was the first sci- 

 entific communication made by Peltier to the Academy of Science : this took 

 place on July 19, 1830; and Peltier dying- October 27, 1S45, it was in this 

 interval of 15 years that he wrote and published the labors and discoveries of 

 which we shall proceed to give a rapid enumeration. 



At the time that Peltier began to devote himself to experiments in physics, 

 Nobili was in Paris, having come thither to illustrate his system of static needles 

 which he had just invented for galvanometers. Peltier was forcibly struck by 

 the sensibility which tliese instruments were rendered capable of acquiring by 

 this ingenious modification, and set himself immediately to work to construct 

 similar ones for himself. A short time afterwards M. De la Rive commenced his 

 publications on the theory of the pile. This illustrious savant wished to prove 

 that chemical action was the real cause of dynamic electricity, and endeavored 

 to demonstrate this by analyzing the difl'erent phenomena of the currents by 

 means of the galvanometer thus perl'ected by Nobili. Peltier thus found him- 

 self led, on one hand, to the thorough study of galvanometers, and on the other 

 to experiments on the pile and on currents. The first communication that Peltier 

 made to the Academy of Science bore marks of this double impulse. On July 

 19, 1830, he presented his note relative to dry piles; May 27, 1833, he laid 

 before this learned body another note on the quantity and intensity of currents ; 

 July 22, of this same year, he presented them with a memorandum on the same 

 subject; and finally, on March 10, 1834, he made known his galvanometer of 

 deviations proportioned to its force. 



Peltier had naturally great dexterity of hand, which had been still increased 

 by his })ractice of horology ; further, he was possessed of patience sufficient for 

 any ordeal, never becoming disheartened, and never recoiling- before an}- sacrifice 

 of time or trouble which could lead to the desired end ; and assisted besides by 

 the counsels of a distinguished artist, M. Gourjon, he was enabled to give to his 

 galvanometers a sensibility which permitted him to study the smallest forces, and 

 consequently to disc(.)ver ])hcnomena of which he would never have suspected the 

 existence had he had at his disposal only heavy and sluggish instruments. It 

 Avas thus he discovered that, under certain determinate circinnstances, a weak 

 electric current can produce cold. He first made known this fact to the Academy 

 of Sciences, April 21, 1834; later he inserted in volume 56 of the Annals of 

 Chcmistrij and Pltijsics a dissertation on the heat generated by electric currents. 



In 1835 Peltier discovered the diff"erence of capacity of the various metals for 

 each kind of electricity. During this same year he published in volume GO of 

 the Annals of Chemistry and Physics a dissertation on electro-magnetic experi- 

 ments. Until that time it had been assumed, for simplicity and facility in theo- 

 retic calculations, that magnetic repulsion was a force equal and contrary to 

 attraction. In this dissertation Peltier proves that it is nothing, demonstrating 

 that repulsion is by no means a special force like attraction, btit that it is an effect 

 of the disagreement of opposed motions sustained in their opposition by second- 

 ary causes and influences. 



In 1830 Peltier again turned his attention to the quantity and intensity of cur- 

 rents, laying before the academy. May 9th, an article on this subject ; and this 

 same year he sul)mitted to that learned body the curious fact of the formation of 

 several individuals proceeding from a single animal that is subjected to lingering 

 inanition. He published in volume 62 of the Annals of Chemistry and Physics 

 a description of the electrometer which he had just invented, and which is cer- 

 tainl}^ one of the most useful instruments with which he has enriched science ; 

 and he also presented to the Philomathic Society most interesting observations 

 on vorticellae, on the articulation of the claws of rhizopodes, on the influence of 

 electric currents in the vegetation and evolution of animalcula, on the reproduc- 

 tion of arcellge, &c. Finally, this same year, recivrring for the last time to the 



