Proceedings of the British Association. 225 



yet having an obvious connection. He then gave a tabular view 

 of the monthly means for 1 843 of the temperature, vapour pressure, 

 gaseous pressure, barometer and humidity ; and pointed out in detail 

 their peculiarities and dependencies ; and concluded by submitting 

 the importance of either admitting or rejecting the propriety of 

 separating the two pressures which unite in forming the total 

 barometric pressure. The remarkable fact recently brought to light 

 by Sir James Ross, as one of the results of his voyage, that the 

 mean height of the barometer is nearly an inch less in the latitude of 

 75° S. than in the tropics, presses the consideration of this point 

 upon our notice ; for it is either explained by the diminution of 

 the vapour constituent in the higher latitudes, which diminution 

 appears nearly to correspond to the decrease of barometric pressure 

 observed by Sir James Ross, — or it is a fact (not hitherto attempted 

 to be explained on any other hypothesis) of so startling a character 

 as to call for immediate attention. 



Col. Sykes said, that there was one point to which, in his opinion, 

 Col. Sabine had not assigned due importance, — viz. the influence 

 of the monsoons. The disturbed atmospheric state during these 

 extended from 52 to 120 days in the year, and gave rise to great 

 fluctuations of the barometer and thermometer. — Prof. Lloyd urged 

 the importance of separating the gaseous pressure from the pressure 

 exercised by the more fluctuating constituent of the atmosphere, 

 and congratulated Colonel Sabine on the advance he had already 

 made in tracing the parts of the entire phenomena due to each ; this 

 he exemplified by pointing out various points of difference between 

 the meteorology and the climate of St. Helena and of Dublin. — Prof. 

 Dove was of opinion that the separation of the gaseous pressure 

 from that of the aqueous does not lead to such simple results as 

 those which he obtained by calculating the observations made at 

 other places. Hence the question might arise, whether this separa- 

 tion was generally applicable. He then showed, that the elasticity 

 of vapour diffused in the atmosphere is so small in the interior of the 

 continent of Asia, that the curve of the whole barometric pressure 

 is of the same form as that found for Europe, when from the 

 barometric pressure we subtract that of the aqueous vapour. By 

 this means, the curves for all places assume the same form, showing 

 a single maximum and a single minimum ; and this as well with 



