SKETCH OF JULES JAMIN. 263 



and of indicating by most striking apparatus the methods of solving 

 many intricate problems. The qualities that Jamin displayed in his 

 oral teaching are found in his " Traite General de Physique," which 

 reproduces his course at the Polytechnic School, and " in which mas- 

 ters as well as pupils find exact descriptions of the actual state of sci- 

 ence." This work was published 1858 to 1861, in three volumes. 



M. Jamin was elected to the Section of Physics in the Academy of 

 Sciences in 1868. In 1884 he was chosen perpetual secretary in the 

 place of Dumas. His address on the anniversary of the admission of 

 M. Dumas to the Academy was regarded as a rare example of pathetic 

 eloquence ; anu in 1885 he delivered an address on the occasion of the 

 centenary of M. Arago, which was characterized by its philosophical 

 examination of the labors of that distinguished experimenter, and its 

 thoughtful analysis of his mental powers, as well as by the clearness 

 with which these points were presented. 



M. Jamin's labors were carried on in very diverse branches of 

 physics ; and he interested himself and became versed in other de- 

 partments of science and art. While studying for the degree in 

 Physics at the Normal School, he also qualified himself for a degree 

 in Natural Sciences. At Caen he took geological and botanical excur- 

 sions with his pupils on Sundays. Of his regular studies he was first 

 occupied with optics. His first memoir, already spoken of, on the re- 

 flection of light from metallic surfaces, was in this line, and was one 

 of the best studies of the kind. Others were his studies of interfer- 

 ences, and of the measurement of the indices of refraction, of gases, 

 of water under different pressures, and of the vapor of water. He 

 discovered the elliptical polarization of light reflected by vitreous sub- 

 stances near the polarizing angle, and the negative elliptical polariza- 

 tion of fluorine ; he published a memoir on colored rings, and invented 

 interference apparatus in which the light reflected on opposed faces 

 of thick transparent rings was utilized. He made discoveries in capil- 

 larity. In 1873 he exhibited a foliated magnet which was capable 

 of carrying twenty-two times its own weight, while the greatest car- 

 rying power attained by artificial magnets previous to that time had 

 been from four to five times their weight. This result was obtained by 

 substituting, for the thick plate hitherto employed, a sufficient number 

 of very thin plates superposed on each other, and all thoroughly magnet- 

 ized. In these and other experiments in electrical science M. Jamin 

 was greatly assisted by the research laboratory which M. Duruy had en- 

 dowed. Among the later fruits of these researches was the perfection 

 of the Jamin electric light, as an improvement upon the Jablochkoff 

 candle. In his description of this lamp, the inventor sums up its quali- 

 ties by saying : " It lights and relights itself as often as is required ; 

 it only requires one circuit for all the neighboring candles ; it replaces 

 automatically those which are entirely consumed, by new carbons ; it 

 employs no insulating material which might alter the color of the 



