JOURNA L 



OF THE 



ASIATIC SOCIETY. 



Tables for determining the Elastic Force of Aqueous Vapour in the 

 Atmosphere and the Temperature of the Dew-point, by Observations 

 of a dry and wet bulb Thermometer ; computed agreeably to Dr. 

 Apjohn's Hygrometric formula, under the direction of CapL J. T. 

 Boileau, of the Bengal Engineers, F.R.S., F.R.A.S. Superin- 

 tendent of the Hon'ble E. I. Company's Magnetic Observatory at 

 Simla. 



The formula of Dr. Apjohn, according to which the elastic force of 

 the aqueous vapour contained in the atmosphere is deduced from the 

 observed temperature of a dry and wet bulb Thermometer freely 

 exposed to evaporation, was first given in the Transactions of the R. I. 

 Academy for 1835, but as a more complete exposition of the theory 

 by which the general expression has been obtained is given in a 

 " Note on the value of the Numerical Co-efficient in the Hygrometric 

 formula applied to the observations of the dry and wet bulb Ther- 

 mometer," by Dr. Apjohn, published with some remarks by Professor 

 Lloyd in the Proceedings of the R. I. Academy for 1840, it will only 

 be necessary to notice the latter paper. 



The following assumed data, form the basis of Dr. Apjohn's investi- 

 gations : — 



No. 147. No. 63, New Series. y 



