' 
ON SOME POINTS IN THE METEOROLOGY OF BOMBAY. 73 
officers, who by voluntarily performing the duties of their absent comrades, 
have enabled them to undertake and perform the duties of the observatories 
without detriment or inconvenience to the service in general. # 
Signed, on the part of the Committee, 
J. F. W. HerscHe. 
On some Points in the Meteorology of Bombay. 
By Lieut.-Colonel Sanine, R.A., F.R.S. 
[A communication read to the Mathematical and Physical Section, and ordered to be printed 
entire amongst the Reports. | 
In a communication which I had the honour to make to the Section at the 
York meeting of the British Association, on the subject of the meteorological 
observations made at Toronto in Canada in the years 1840 to 1842, I noticed 
some of the advantages which were likely to result to the science of meteor- 
ology, from the resolution of the barometric pressure into its two constituents 
of aqueous and of gaseous pressure. It was shown that when the constituents 
of the barometric pressure at Toronto were thus disengaged from each other 
and presented separately, their annual and diurnal variations exhibited a very 
striking and instructive accordance with the annual and diurnal variations of 
the temperature. The characteristic features of the several variations when 
projected in curves were seen to be the same, consisting in all cases of a single 
progression, having one ascending and one descending branch; the epochs 
of maxima and minima of the pressures being the same, or very nearly the 
same, with those of the maxima and minima of temperature; and the corre- 
spondence in other respects being such as to manifest the existence of a very 
intimate connexion between the periodical variations of the temperature, and 
those of the elastic forces of the air and vapour. The curve of gaseous pres- 
sure was inverse in respect to the other two; that is to say, as the tempera- 
ture increased the elastic force of the vapour increased also, but that of the 
air diminished, and vice versd ; and this was the case both in the annual and 
the diurnal variations. 
Such being the facts, I endeavoured to show, in the case of the diurnal va- 
riations, that the correspondence of the phenomena of the temperature and 
gaseous pressure might be explained, in accordance with principles which 
had been long and universally admitted in the interpretation of other meteo- 
rological 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 consequent re- 
ception of the overflow from other portions of the atmosphere, 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,—|st, 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, constituting a diurnal variation in the force of the wind at the place 
of observation, which should also correspond with the variations of the tem- 
perature in the epochs of its maximum and minimum, and intermediate gra- 
dation of strength. The anemometrical observations at Toronto were shown 
to be in agreement with the view which had been then taken, confirming the 
