*of the Mauritius. 137 



to defray the expense of a course of practical chemistry, which 

 had been commenced, and in which several of the natives were 

 lending their aid, who, by their previous education, had been 

 prepared to understand that science. 



Mr. J. N. de Casanova was elected a Member of the Society. 

 He presented a pamphlet, of which he is the author, entitled 

 Examcn de las Ayuas Minsralcs de Sun Pedro; nolicias topo- 

 '/ra/icas da supartidoy sus propricdudes Medicas. 



Mr. Bernard, Provost of the Royal College, was also elected 

 a Member. 



May f7, and June 14. — Mr. Lienard (Father) read a descrip- 

 tion of two fishes of our island ; one of thern is known to the 

 fishermen by the name of Battoir, and, as it presents none of 

 the characters which would serve to arrange it amid the genera 

 of the fan. Ay of Percoides, to which however it belongs, it has 

 jn the mean time received the name of Platcsome. Mr. E. 

 Lienard presented a figure of this fish. The other, which 

 fishermen call Lion M/ile, as a Holoceiilrus, but is not, in the 

 "opinion of Mr. Lienard, the H: Sammer. (Cuv. &Val.) Neither 

 of them is used as food. 



Mr. J. Lienard read the description of a Crab, of the genus 

 Portunus, of which he also presented a figure. It is one of those 

 eaten in the island. lie also read a description and presented 

 the figure of an Acunthurus, which is very rare in our seas. 



Mr. Faragnet presented and explained a table, constructed 

 by him, to represent geometrically the law of the variation of 

 temperature in the sea, at different depths. He founded his , 

 construction on the experiments made on board the Astrolabe, 

 which alone in regard to this subject are worthy of trust. They 

 show that at the depth of 820 fathoms, the temperature is u°.4 

 • Cent. (43° Farnh.), and the curve representing the rate of va- 

 riation, is a parabola of a high order, having for its asymptote 

 a vertical line corresponding to the temperature of 4° or 5° 

 Cent. At the depth of 1000 fathoms, a cylinder of copper-plate, 

 more than three lines thick, was crushed ; which is easily ac- 

 counted for, when we calculate the pressure it had to sustain. 



Mr. Barry presented a' notice of the temperature of mines at 

 different depths. By observation made in the Cornish mines in 

 1815, it results, that at the depth of 1400 feet (English), the 

 temperature of mines exceeds that of the surface of the earth by 

 about 28° Farnh. and that the heat augments in proportion to 

 the depth, at the rate of about 1® for 65 feet. 



Mr. J. Desjardins read a notice of certain species found in 

 the Isles of France and Bourbon. He also, in conjunction with 

 Mr. L. Bouton, read a memoir regarding the naturalist Com- 

 ix 



