76 REPORT—1840. 
of the constituent effects will also be wnder estimated, or the 
climateric effect of the sun will come out too small. 
107. Such, indeed, is almost certainly the case. The climateric 
effect of the sun at Paris is estimated from the superficial range 
of temperature (deduced by Poisson from Arago’s experiments) 
to be only 24° cent.*. The mean temperature of Paris being 
11° cent., there remains for the temperature which would re- 
main if the direct influence of the sun were removed, — 13° c. 
or + 9° Fahr., a result altogether improbable. Further, the 
thickness of a sheet of ice over the whole globe which would be 
melted by the entire annual action of the sun, would be, accord- 
ing to Poisson, seven or eight metres}, whilst Pouillet supposes 
it four times as greatf. 
108. Fourier, in his remarkable Memoir on the Heat of the 
Globe§, had clearly shown that its superficial temperature 
depends on three causes, which may be kept wholly distinct. 
1. Solar heat. 2. Temperature of space. 3. Internal heat. To 
these M. Poisson has added Atmospheric Heat, which, however, 
is merely that part of the solar heat absorbed by the atmosphere 
and communicated secondarily to the earth, independent of that 
received by direct radiation. 
109. Since the Report of Prof. Whewell on the Mathematical 
Theory of Heat, to which we refer for what had been written 
on these subjects at that time, several new contributions to 
this interesting branch of science have been made, both theore- 
tically and experimentally ; I allude particularly to the publica- 
tion of Poisson’s Theory of Heat, and Pouillet’s Memoir before- 
cited. 
110. Poisson’s Theory of ArmospHeRic Hear has met witha 
very just criticism, in almost every part of which I entirely agree, 
at the hands of Prof. Auguste de la Rive, of Geneva. His ob- 
jections are so ably and clearly stated, that so far as they antici- 
pate my own, it may be sufficient briefiy to state them, and refer 
to his article || for details. And first, as to the constitution of 
the atmosphere: Poisson{], adopting the reasoning of Fourier**, 
admits that the temperature of any part of the atmosphere must 
be determined by the equality of the heat directly received from 
the sun and indirectly from the earth, with that radiated abroad 
* Poisson, p. 518. + Poisson’s Supplément, p. 7. 
t Mémoire sur la Chaleur Solaire, p. 9. (See above, art. 78.) 
§ Mémoires de l Institut, vii. 569 ; and Whewell’s Report, in British Associa- 
tion, Fifth Report, p. 30. 
\| Bibliotheque Universelle, Nov.—Dec., 1835. 
4 Théorie, p. 448, &c. ** Mém. de l'Institut. vii. 584, &c. 
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