1 



the Meteorology of Bombay, '%& — 



Such being the facts, I endeavoured to show, in the case of the. 

 diurnal variations, that the correspondence of the phenomena of the 

 temperature and gaseous pressure might be explained, in accord- 

 ance with principles which had been long and universally admitted 

 in the interpretation of other meteorological phenomena, by the 

 suppositions, — of an extension in height and consequent overflow in 

 the higher regions of the atmosphere of the column of air over the 

 place of observation, during the hours of the day when the surface 

 of the earth was gaining heat by radiation, — and of a contraction of 

 the column during the hours of diminishing temperature, and conse- 

 quent reception of the overflow from other portions of the atmo- 

 sphere, which in their turn had become heated and elongated. 



According to this explanation there should exist, during the hours 

 of the day when the temperature is increasing, — 1st, an ascending 

 current of air at the place of observation, of which the strength 

 should be measured by the amount of the increments of temperature 

 corresponding to given intervals of time; and 2nd, a lateral influx of 

 air at the lower parts of the column, of proportionate velocity, con- 

 stituting a diurnal variation in the force of the wind at the place of 

 observation, which should also correspond with the variations of the 

 temperature in the epochs of its maximum and minimum, and inter- 

 mediate gradation of strength. The anemometrical observations at 

 Toronto were shown to be in agreement with the view which had 

 been then taken, confirming the existence of a diurnal variation in 

 the force of the wind, corresponding in all respects with the varia- 

 tion of the temperature. 



Admitting the explanation thus offered to be satisfactory in re- 

 gard to the diurnal variations, it was obvious that the correspond- 

 ence of the annual variations of the temperature and pressures might 

 receive an analogous explanation. 



A comparison of the results of the observations at Toronto with 

 those of the observations of M. Kreil at Prague in Bohemia, (pub- 

 lished in the Mag. und Met. Beob, zu Prag, and in the Jahrhuch 

 fur Prag. 1843,) showed that the characteristic features of the pe- 

 riodical variations at Toronto were not peculiar to that locality, but 

 might rather be considered as belonging to stations situated in the 

 temperate zone and in the interior of a continent. The annual and 

 diurnal variations at Prague were also single progressions, and the 

 same correspondence was observable between the variations of the 

 temperature and of the gaseous pressure. 



The publication of the volume of magnetical and meteorological 

 observations made at Greenwich in 1842, which took place shortly 

 after the meeting of the Association at York, enabled me to add a 

 postscript to the printed statement of my communication in the an- 

 nual volume of the Association Reports, showing the correspond- 

 ence of the results at Greenwich with the relations which had been 

 found to exist in the periodical march of the phaenomena at Toronto 

 and at Prague. 



From the concurrence of these three stations, it was obvious that a 

 considerable insight had been obtained into the laws which regulate 



