REPORT ON METEOROLOGY. 
207 
more such gases or vapours as we have been describing are 
put together, either into a limited or an unlimited space, they will 
finally be arranged, each as if it occupied the whole space and the 
others were not present; the nature of the fluids, and gravita¬ 
tion, being the only efficacious agents*.” Upon this principle, 
then, Mr. Dalton conceives that the total weight of the gases 
existing in the atmosphere which they compose, is proportional 
to the volumes existing at the surface of the earth. Thus taking 
the pressure of the nitrogen and oxygen together at thirty 
inches, he conceives that the particular pressure exerted by 
each is as 79 to 21, being the ratio of their volumes; con¬ 
sequently 23'7 inches of pressure result from the atmosphere of 
the former, and 6*3 inches from that of the latter. The weight 
of the aqueous atmosphere is variable, and may be assumed at 
0*4 inch, and that of carbonic acid at *03 inch. Mr. Dalton 
computes the height of the respective atmospheres to be 
fifty-four miles for nitrogen, thirty-eight for oxygen, carbonic 
acid ten miles, and aqueous vapour fifty miles. He justly ob¬ 
serves, that the condition of the earth’s atmosphere may be 
much modified by the disturbance to which it is subjected, and 
suggests the inquiry as an experimental rather than a purely 
theoretical one. It is to be hoped that the experiments which 
Mr. Dalton has promised to publish on the subject, may soon 
be given to the world. 
Mr. Daniell’s Essay on the Constitution of the Atmospheref 
will require little notice here, both because it has been a con¬ 
siderable time before the public, and because, its object being 
an extension in some detail of Mr. Dalton’s original views, it 
does not readily admit of abridgement. Mr. Daniell has suc¬ 
cessively considered the habitudes of a gaseous atmosphere, 
one of aqueous vapour, and a mixed atmosphere such as the 
globe actually possesses. He has illustrated at great length 
what he conceives to be the particular course of phenomena, 
chiefly by means of Tables, which he has carried to a consi¬ 
derable extent. These tables are intended to give a general 
idea of the influence of temperature, the rotation of the globe, 
and other circumstances in producing currents, of which Mr. 
Daniell has endeavoured to establish the velocity and other 
characters, and has applied them to the explanation of various 
meteorological phenomena. 
M. Theodore de Saussure has published an extended me¬ 
moir J upon the variations of the quantity of carbonic acid in 
the atmosphere, upon which he has made an elaborate series of 
* Phil. Trans, ut supra, p. 184. f Meteorological Essays, p. 1—137. 
X Annates de Chimie, xliv. 1—55. 
