MEMOIR OF PELTIER. 163 



What is electricity ? Peltier liad now come to the study of this science — a 

 stmlv which was to occupy him exclusively during the last twenty years of his 

 life, and on which he has left such a profound impress of his genius; but we see 

 what detours he had made before arriving at this point, and what road he had 

 travelled. 



I have entered into these details because they seemed to me to offer some, 

 1 interest ; we see in them the gropings to which a vigorous mind may give itself 

 up before arriving at what is destined to constitute one day its study from pre- 

 dilection. The course followed by Peltier is, besides, I think, rooted in tlie 

 very nature of the human mind ; it is always towards the most abstract and 

 complex ideas that man at first and from choice directs his studies ; it is not 

 until later, and little- by little, that, instructed by experience, he at tlie same 

 time simplifies and restricts his researches. History bears ample testimony to 

 this. In the middle ages, on the revival of. letters, men were occupied but with 

 questions in metaphj^sics — the nature of the soul and its faculties — and, as if this 

 were not sufficiently beyond their powers, they discoursed even on the nature 

 of God. It was not until some time later that they consented to descend from 

 these heights and stud}^ the material world : first the living world, anatomy and 

 physiology ; and lastly the inorganic world, physics, chemistry, geology, &c., 

 &c. ; so true is it that associated men, or the people, take but the same com'se as 

 isolated men, or individuals. 



It was about 1825 that Peltier commenced seriously to study physics; until 

 that time indeed it had been to him but an accessory. In 1827 he bought in a 

 public market-place an old electric machine and some Leyden jars ; these 

 were the first instruments he had at his disposal. At first he amused himself by 

 di'awing sparks; he then formed sparkling squares and tubes, and electric j ump- 

 ing- jacks, and many other amusing objects; a little after he tried more serious 

 experiments; but he very soon discovered that this road could lead to nothing. 

 By an electric machine, in fact, he could never have obtained other than static 

 electricit}'^; and static phenomena constantly reducing themselves to phenomena 

 of attraction or repulsion, and to sparks, are very far from offering the variety 

 and interest of dynamic phenomena. Weary of these experiments without result, 

 Peltier very naturally turned his attention towards another som'ce of electricity, 

 the pile ; it was, besides, of the Voltaic pile that physiologists made use in apply- 

 ing electricity to the phenomena of life. Peltier therefore very soon bought a 

 trough pile, with which he made his first investigations into currents. Later he 

 made for himself a very great number of these piles. 



For several years Peltier labored without communicating to any one either his 

 W'ork or his discoveries. Knowing but little of the world, he had not had oppor- 

 tunit}^ to compare himself with other men, and, ignoring completely the real 

 worth of his intellect, did not dream that he could do anything worthy of being 

 known. This diffidence rendered him extremely reserved, and he worked a long- 

 time in profound silence. His first communication to the Academy of Science 

 was on the 19th of July, 1830, and relates to dry electric piles. The reason of 

 this communication was as follows : It had been generally believed for a long- 

 time that dry piles were not capable of giving a constant current, and could not 

 produce any chemical inactions. In 1830 M. Donne endeavored to throw light 

 on this subject b}- new investigations. In his experiments he carried the number 

 of couples to 25,000 and 30,000, without, however, increasing the usual size o? 

 the plates. He obtained thus phenomena of enormous tension, but could not 

 get a current which was capable of effecting the least chemical action. 



At this time Peltier had already comprehended the distinction to l)e main- 

 tained between the quantity and the intensity of a current. He therefore took 

 up the experiments of M. Donne, but instead of increasing the number of couples, 

 he increased their surface, and thus succeeded in reddening to the color of turnsole, 

 and in decomj)Osiug water by means of a cm-rent of the dry pile. It suffices 



