42 REPORT—1840. 
memoirs, which may assist the researches of others, and en- 
able them to draw their own conclusions. 
I.—TEMPERATURE. 
15. Meteorology may, in some sense, be considered as a 
mere branch of the science of heat in its widest application. 
Were our globe and atmosphere in a uniform state with re- 
gard to heat, and not subjected, by astronomical and cosmical 
laws, to perpetual and material changes in the distribution of 
temperature in its solid, fluid, and gaseous parts, the simplest 
considerations would suffice for the solution of the few pro- 
blems which could then be called meteorological. 
16. It is to the different inclination of the solar rays, that 
we trace the effect of climate varying with latitude, and of cli- 
mate varying with season. It is to the unequal absorption and 
radiation of heat by seas and continents, that we ascribe the 
curious inflections of the isothermal lines, and the characters 
of moderate and excessive climates. It is to the combination 
of these causes with the rotation of the globe, that we attribute 
all the phenomena of wind, from the steady monotony of the 
Trades, to the capricious changes of higher latitudes, the Tor- 
nados of America, and the Typhoon of the Chinese seas. It is 
to the mechanical transport of great masses of air due to 
change of temperature and consequent expansion, that we look 
for the explanation of most of the irregular, and several of the 
periodical barometric fluctuations. Lastly, it is to the varying 
conditions of temperature proper to the day and night, to one sea- 
son and another, in high latitudes and low, that we look for prin- 
ciples to guide us in the difficult, but important determination of 
the hygrometric elements of our atmosphere, the ceaseless mo- 
difications of that fluctuating ocean of vapour which floats in- 
dependent of, and unobstructed by, the permanently elastic 
envelope of our globe, which (though comparatively unheeded 
by us) is subject to all the variations of pressure and tempera- 
ture of the common atmosphere, but through limits far wider, 
and to changes of physical condition, which the other, from its 
permanent character, never presents. 
17. If we choose, then, to consider the grand meteorological 
problem for a moment synthetically, instead of analytically— 
T mean, by regarding the known causes which influence cli- 
mate, and applying to these the laws of distribution and com- 
munication of heat, which are deduced from laboratory experi- 
ments, and from the first data or experimental axioms of that 
science,—we have, at least, the advantage of perceiving the 
magnitude, interest, and definitiveness of the problems with 
