1827.] 



Proceedings of Learned Societies. 



311 



was divided between M. Pons, director of the 

 observatory at Florence, and M. Gambart, of 

 thnt of Marseille, for having observed or cal- 

 culated the three last, comets. M. Montyon's 

 prize in experimental philosophy was be- 

 stbvved on M. Adolphe Brongniart. Two 

 prizes were given for improvements in the 

 healing art to M. M. Pelletier and Caventon, 

 who discovered the sulphate of quinine ; and 

 to M. Civiale, who first succeeded in break- 

 ing the stone in the bladder, and has con- 

 tinued the practice with success. Several 

 medals of encouragement were bestowed 

 for minor considerations. The prize in sta- 

 tistics was equally divided between M. M. 

 Braylo and Cardeau. After these prizes had 

 been distributed, and the subjects proposed 



for the ensuing year, an historical eulogium 

 would have been pronounced uponM. Charles, 

 who is principally known for the invention 

 of balloons which were substituted for those 

 of Montgolfier, by M. Tourier j but that gen- 

 tleman was too ill to attend. M. C. Dupin 

 explained the statistical researches in refer- 

 ence to the cabals of the north and south of 

 France, and drew a comparison between the 

 means of executing them in the reign of Louis 

 XIV. and at present. M. G. Cuvier then 

 read an historical panegyric upon Conizart; 

 and M. Cordier communicated an extract 

 from his memoir on the interior temperature 

 of the globe. There was not time to allow 

 the panegyric of M. Penil, by M. G. Cuvier, 

 being read. 



VARIETIES, SCIENTIFIC AND MISCELLANEOUS. 



August's Psychrometer. A German phi- 

 losopher, of the name of August, when com 

 paring the temperature produced by evapo- 

 ration and that of the circumambient air at 

 the same time or, in other words, com- 

 paring the difference of temperature indi- 

 cated by a moistened and a dry thermometer 

 with the difference of temperature of the 

 interior and exterior thermometer of Daniel's 

 hygrometer, or the diminution of tempera- 

 ture necessary to produce a deposition of 

 dew found that the first was very nearly and 

 pretty constantly the half of the second, at the 

 moment of condensation. This ratio being 

 established, it is only necessary to compare a 

 moistened thermometer with a plain one to 

 determine the variable quantity of water 

 contained in the atmosphere. A particular 

 combination of the instruments for facilitating 

 these observations, M. A. has named a psy- 

 chrometer, from J>v?o; (cold). The nearer 

 the temperature indicated by the two ther- 

 mometers constituting the psycrometer ap- 

 proach, the more moist will the air be ; and 

 twice the difference of the two indications 

 will tell how much the temperature should be 

 lowered to produce condensation of ibe at- 

 mospheric vapours. The ratio between the 

 psychrometer and Daniel's hygrometer is not, 

 however, absolutely constant and universal, 

 and holds good exactly only in the ordinary 

 state of the barometer (from 331 to 340 Pa- 

 risian lines), and at mean temperatures (from 

 10 to 24 Reaumur). The mathematical for- 

 mula of M. August, for expressing the quan- 

 tity of vapour contained in the air, is 



<"- 



e being the tension of the atmospheric va- 

 pour, or its expansive force ; t the tempera- 

 ture of the air ; t 1 the cold produced by the 

 evaporation of a moistened thermometer ; e' 

 the maximum tension of the vapour, corres- 

 ponding to the temperature t 1 , and reduced 

 to the state of the barometer ; b the height 



of the barometer, expressed by unity at 0, 

 the same as the tension of the vapour ; y the 

 specific heat of dry air, =0-2669, according 

 to Kiot ; k that of the aqueous vapour, 

 =2-847; I the density of the vapour, com- 

 pared with that of dry air, =0'62349 (Kiot) ; 

 x the latent heat of vapour, according to M. 

 Gay Lussac, 550 of the centigrade scale. 

 M. August observes, that Daniel's hygro- 

 meter cannot exactly indicate the quantity of 

 vapour contained in the atmosphere, because 

 the exterior surface of the instrument has 

 constantly a higher temperature than is indi* 

 cated by the interior thermometer. The 

 error is greater, as the difference between 

 the temperature of the point of precipitation 

 and that of the air is greater disadvantages, 

 to which the psychrometer is not liable. The 

 indications, however, of this latter instrument 

 are greater in the sun than in the shade an 

 effect arising from the radiation of heat. The 

 same results are observable in the morning 

 and in the evening. Whether this instrument 

 can be employed in winter, the inventor has 

 not yet determined. At all events, it is ne- 

 cessary to substitute for the value of x=5,50 

 X=550+75 =625 if there be a formation 

 of ice. In general, the indications will be 

 more perfect as the values of y and k shall be 

 better known. The approximative formula 

 calculated for the mean heights of the ba- 

 rometer, gives e=J 0-26 (t t 1 ) in Pa- 

 risian lines. 



Diamonds in Siberia. rThe platiniferous 

 sand of Nischni-Toura, in Siberia, offering a 

 striking analogy to that of Brazil, in which 

 diamonds are generally found, has led to an. 

 expectation of their being discovered in that 

 inhospitable region. The sand of Brazil is 

 principally composed of rolled fragments of 

 hydrate of iron and jasper, and contains more 

 platinum than gold. The sand of Nischni- 

 Toura is visibly formed of the same compo- 

 nent parts ; and the presence of hydrate of 

 iron is the more remarkable, as it is in a 

 conglomerate of this species that the Bra- 

 zilian diamonds are enveloped as if these 

 two minerals were not accidentally combined, 

 but were the remains of one and the same 



