Intelligence and Miscellaneous Articles. 77 



his morning occupations. The wear and teai", however, of a life 

 devoted to such constant study, and the total neglect of exercise and 

 healthy recreations, finally undermined his naturally vigorous con- 

 stitution, and in the autumn of 1838 the alarming discovery was 

 made that he was labouring under the fatal disease of water in the 

 chest. The efforts of his physicians contributed for a time to mitigate 

 the more serious symptoms of his malady ; but every relaxation of 

 his sufferings led to the resumption of his labours ; and to the 

 earnest remonstrances of his friends, and the entreaties of his family, 

 he was accustomed to reply, that to him la vie cetait le travail; nay, 

 he even undertook to conduct the usual examinations of the Ecole 

 Polytechnique, which occupied him for nearly ten hours a day for 

 the greatest part of a month. This last imprudent efibrt ended in an 

 attack of paralysis, attended by loss of memory and the rapid ob- 

 scuration of all his faculties; he continued to struggle, amidst alter- 

 nations of hope and despondency, for a considerable period, and died 

 on the 25th of April last, in the fifty-ninth year of his age. 



Poisson was eminently a deductive philosopher, and one of the 

 most illustrious of his class ; his profound knowledge of the labours 

 of his pi'edecessors, his perfect command of analysis, and his extra- 

 ordinarj^ sagacity and tact in applying it, his clearness and precision 

 in the enunciation of his problems, and the general elegance of 

 form which pervaded his investigations, must long continue to 

 give to his works that classical character, which has hitherto been 

 almost exclusively appropriated to the productions of Lagrange, 

 Laplace, and Euler. If he was inferior to Fourier or to Fresnel in 

 the largeness and pregnancy of his philosophical views, he was in- 

 comparably superior to them in mathematical power : if some of his 

 contemporaries rivalled or surpassed him in particular departments 

 of his own favourite studies, he has left no one to equal him, either 

 in France or in Europe at large, in the extent, variety, and intrinsic 

 value of his labours. 



The last work on which he was engaged was a treatise on the 

 theory of light, with particular reference to the recent researches of 

 Cauchy : iiearly two hundred pages of this work are printed, which 

 are altogether confined to generalities, whose applications were 

 destined to form the subject of a second and concluding section : 

 those who are acquainted with tiie other works of Poisson will be 

 best able to appreciate the irreparable loss which optical science 

 has sustained in the non-completion of such a work from the hands 

 of such a master. 



XIV. Intellige7ice and Miscellaneous Articles. 



LEPIDOMliLANE — A NEW MINERAL. 



THIS mineral comes from Pirsberg in Wermeland, Sweden, and 

 aj)pears to be a species of mica differing from others. It has 

 been analysed by M. Soltman in M. Wohler's laboratory. 



This mineral is a granular and schistose aggregate of small cry- 

 stals in scales, which seldom exceed half a line in diameter ; their 



