SUPPLEMENTARY REPORT ON METEOROLOGY. 43 
which meteorology, in the philosophical sense of the term, is 
conversant. Those who limit themselves to a few daily mecha- 
nical observations of the barometer and thermometer, or who 
even apply the results of these simple, but (if wel! conducted) 
important observations, are little aware that the science they 
cultivate is capable of giving definite answers to questions 
which might seem further removed from human apprehension 
than even the problems of physical astronomy, such as the con- 
dition of the interior of our globe with respect to temperature,— 
and in some degree its history as regards periods of geological 
convulsion,—the whole measure of solar heat received by our 
globe in a given time,—the condition of the highest, and for ever 
inaccessible parts of our atmosphere,—the temperature which 
reigns in the vast regions of space, remote from the influence of 
any planet or satellite, however small, whose presence and pro- 
per heat would yet influence such an experiment ;—these are 
amongst the great cosmical problems which we do not mean to 
say have been solved, but which there is little reason to doubt 
that we are in the fair way of one day being able to solve by 
instruments such as we now possess, with the aid of theoretical 
investigations identical in kind with many which have been 
completely mastered. 
18. Of Instruments, those which are most called for are such 
as acquaint us with certain physical constants, or approximate 
constants, which determine for our globe and its atmosphere 
the particular application of the general laws of the Conduc- 
tion and Radiation of Heat. Of theoretical Investigations, 
WG require such as shall solve with sufficient generality the 
problems with which we have to deal, but stripped of those 
exuberant claims to mathematical precision which cramp their 
application and discourage those who know how far we are 
from even the chance of ever attaining to a degree of accu- 
racy which such niceties pre-suppose. The theoretical in- 
vestigations of most use, then, are those which, taking the pro- 
blem in a general way, show exactly upon what arbitrary con- 
stants the determination (for instance) of the climateric condition 
of any point of the globe at any moment depends. This is a 
task of no smal] difficulty, even in the simplest form in which it 
can be put. 
19. It infers a knowledge (1) of the fundamental laws or 
axioms of the science of heat (such as the law of expansion, 
variation of specific heat with density, conduction, radiation). 
(2) Of all the physical circumstances which can possibly influence 
the temperature of our globe, that is, the communication of heat 
to, or abstraction from it (1 mean their existence, not their de- 
