164 MEMOIR OF PELTIER. 



for this that we take from 25 to 30 disks, provided only that their surface be a 

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

 entific communication made Ijy 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, 

 Ni.ibili was in Paris, having come thither to illustrate his system of static needles 

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

 the sensibility which these instruments were rendered capable of acquiring l)y 

 this ingenious modification, and set himself immcdiatel}' to work to construct 

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

 ])ublications 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 different phenomena of the currents by 

 means of the galvanometer thus perfected 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 inq^ulse. 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 Avith 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, Avhicli had been still increased 

 by his practice of horology ; further, he was possessed of patience sufiicient for 

 any ordeal, never becoming dislieartened, and never recoilino- before any 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 

 Gonsequentl}^ to discover phenomena of Avhich 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 circumstances, a Aveak 

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

 of Sciences, April 21, 1S34; later he inserted in volume 56 of the Annals of 

 Chemistn/ and Plnjsics a dissertation on the heat generated by electric currents. 



In 1835 Peltier discovered the difference of capacity of the A'arious metals for 

 each kind of electricity. During this same year he published in A'Olume CO of 

 the Annals of Cliemlsiry and Fhtjsks 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 Avas 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, but 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, ^lay 9th, an article on this subject ; and this 

 same year he submitted 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 publislied in volume G2 of the Annals of Chcmistrij and Plii/stcs 

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

 tainly one of the most useful instruments Avith which he has enriched science ; 

 and he also presented to the Philomathic Society most interesting obserA'ations 

 on vorticellse, on the articulation of the claws of rhizopodcs, on the influence of 

 electric currents in the vegetation and eA'olution of animalcula, on the reproduc- 

 tion of arcellte, &c. Finally, this same year, recm-ring for the last time to the 



