JOURNAL 



OF THE 



ASIATIC SOCIETY OF BENGAL. 



Part II.— PHYSICAL SCIENCE, 

 No. II.— 1876. 



VII. — An Account of Experiments made in 1875 and 1876 in various parts 

 of India, for the purpose of comparing the observed Temperature of the 

 Dew-point toith that computed from the JPsychrometer by different 

 Methods of Reduction. — By Henry F. Blanfoed, F. Q. 8., Me- 

 teorological Reporter to the Government of India. 



(Keceived May 29th ;— Bead June 7th, 1876.) 



The observations of which the results are detailed and discussed in 

 this paper, were made with the special object of ascertaining how far 

 the usual methods of computing the hygrometric state of the atmosphere 

 from observations of the dry and wet bulbs thermometers, under the 

 conditions* now adopted at Indian meteorological observatories, afford 

 trustworthy results ; more especially in the extremely dry atmosphere 

 of the interior of India during the hot season. The observations are to a 

 certain extent desultory, having been made during inspection tours in 

 different parts of India, and under various conditions of exposure ; and the 

 results shew some discrepancies, greater than might be expected from more 

 systematic work, and had there been means at hand to introduce siich im- 

 provements in the maniptilation of the hygrometer as experience. has sug- 

 gested. Causes of disturbance, which would produce but little effect in a 

 more humid atmosphere, become influential when the dew point is 10° and 



* The thermometers are exposed on a frame with 1 or 2 cross bars (generally pro- 

 tected "by wire netting at back and front) under a thatched shed open on all sides to 

 the wind. "Where properly constructed the shed is 20 ft. long by 12 ft. wide, but some 

 are smaller than this. 



