Tiii APPENDIX. 



can be turned to any useful purpose., and if we could obtain similar abstracts from 

 other chief stations on the Indian continent, the advantages would be much en- 

 hanced by the correct comparison we should be enabled to draw of their relative 

 climates, the light which would be thrown upon the origin, course and extent of the 

 hot winds; the altitude of different places ; and other interesting phenomena. 



My own observations have now been continued for two years, but I shall only 

 give at length those for the latter year, as the instruments then used were more nu- 

 merous and complete. For the sake of perspicuity I will notice under separate 

 heads the subjects of Barometrical pressure, temperature, and hygroraetry, 



I. The Atmospheric Pressure. 

 The Barometer used is by Dollond, having a window of talc adapted to the re- 

 servoir to shew the level of the mercury. Notwithstanding this however, by a 

 careful comparison with Captain Herbert's instrument, it stands .070 lower than the 

 Barometer at the Surveyor General's Office in Calcutta. Indeed very few can be 

 found to agree perfectly, nor is it necessary provided their difference be once ascer- 

 tained. Mine stands nearly the mean of five that were examined together. 



The amount of the daily oscillation of the Barometer is not shewn by my table as 

 I was unable to observe at the hour of the maximum, 10 o'clock A. M. The differ- 

 ence however between the evening and noon height for each month shews a greater 

 oscillation during the hot months, when the daily change of the thermometer is also 

 the greatest. The close connection between the rise of the thermometer and fall of 

 the barometer is confirmed by the following comparison which the kindness of my 

 friend Dr. A. Russell permitted me to calculate from a diary of three years kept by 



himself* 



Dr. Russell. Benares. 



Month. Mean daily range of (he Barometer. Mean range of the Thermometer, 



21.5 

 21.0 

 21.0 

 26.5 



* In the year 1824 I shall register the Barometer and Thermometer at 10 A. M. and 5 P. M. on par- 

 pose to ascertain the amount of daily oscillation. 



January, 



0.073 



February, 



0.098 



March, 



0.093 



April, 



0.103 



