Doubtless, the mean pressure of the atmosphere, in summer, in the northern hemisphere, is less than in winter, in some localities, and greater in others, and it differs in different countries of equal temperature. And this is all very intelligible. The mean of the pressure for the month is made up by _averaging_ all the _elevations_ and _depressions_. During a month, showing a very low mean, the barometer may, at times, attain its _highest altitude_, if the depressions below the mean are great or more frequent. The barometer is depressed during storms, and ranges high during _set fair_ weather. Ordinarily, therefore, the more stormy the season the more diminished the mean pressure; and it is a mistake to look to an overflow to account for the fact. The changes in the location of the atmospheric machinery, and consequent change in the amount and severity of falling weather, and the periodic frequency and character of storms, and consequent _periodic_ depressions and elevations of the barometer, explain the annual mean variations, as they do the other phenomena. But it is perfectly consistent with the calorific theory to attempt to account for these differences by another of those ever-necessary modifications, viz.: the different tension and elasticity of aqueous vapor in different countries of equal temperature; and then to _suppose_ an expansion of the whole body of the atmosphere and a lateral overflow from the place where the air is expanded, on to some other, where it is not; and thus _suppose_ all necessary currents in the upper regions, setting hither and yon, by the force of gravity alone. And apparently he who is best at supposition becomes the most distinguished meteorologist. Perhaps I have already said all that I ought to be pardoned for saying, in relation to the utter absurdity of attributing all meteorological phenomena to the agency of heat; but when I find such views as those which that article contains, emanating from so distinguished a man, sanctioned by the President of the British Association, and copied into the leading journal of science in this country, I can not forbear a further and a somewhat critical examination of them. There is more error of supposition and less truth in it, than in any other article regarding the science, of equal length, which has fallen under my notice.