SUPPLEMENTARY REPORT ON METEOROLOGY. 45 
of the process. Secondly, the mathematician requires the ut- 
most resources of his analysis to obtain in a definite and tangi- 
ble form the resultant action (we will suppose that tempera- 
ture is the question) of all the heating and cooling influences 
upon acertain point, whose coordinates are given (including 
elevation in the atmosphere, or depression below the surface), 
and at a particular instant of time. And in this investigation 
he will, as we have said, chiefly show his skill in the precision 
which he gives to his results, the judgement with which he intro- 
duces needful approximations at that stage of the investigation 
which shall tend most to simplicity, and in the exhibition of his 
results in forms adapted to experimental verification. Then 
follows the duty, in the third place, of the observer, or practical 
meteorolegist, which is to follow the indications which theory 
assigns for the determination of data, and for which the me- 
thods will be indicated by a competent knowledge of experi- 
mental philosophy, and even by prolonged tentative researches in 
the laboratery. It is not unoften the provoking result of the 
labour expended by the two first sections of investigators, that 
the whole problem is found to turn upon certain quantities, 
whose nature is perfectly well understood, but which are, 
and threaten for ever to remain perfectly unknown. I need 
hardly stop to point out that such a threefold division of labour 
is to be found in many other sciences, and notably at present in 
that of magnetism. A right appreciation of the steps leading 
to the solution of such complex mixed problems, which in fact 
involve a whole science, is the first step to their solution; and 
we commonly find that this is performed by the appearance of 
some master mind, capable of seizing the question in all its ex- 
tent and under every one of these forms—depending on a ver- 
satility of mental endowment of no common order. This is 
what Newton did for the science of gravitation, what is now 
being done by the union of many for the science of optics, and 
what Gauss has pre-eminently done for the science of mag- 
netism. 
22. It will conduce to clearness if it is understood, that so far 
as possible, in what follows, we shall keep in view these different 
aspects of meteorological science ; and combining, as on a for- 
mer occasion, the bibliography with the general detail, I shall 
proceed to the different parts of the science of Temperature 
somewhat in the order adopted in the last report. 
