Leslie on Meteorology. 175 
mention of the labours of Dalton, Gay-Lussac, Biot, Daniell, 
and several others, who have written most ably and ingeni- 
ously on hygrometric phenomena. 
But if our author be somewhat chary in his account of the re- 
searches of his rivals in scientific fame, he has been abundantly 
profuse of his own lucubrations, a few of which seem both inge- 
nious and plausible, but others are so fantastic and extrava- 
gant, as to make us wonder how a gentleman of Mr. Leslie’s 
attainments could wantonly bring his philosophical reputation 
into jeopardy by their serious enunciation. 
After exposing the fallacy of the meteorological cycles, hi- 
therto offered, Mr. Leslie proposes to establish meteorology on 
a solid basis, by first inquiring into the extent and constitution of 
the medium which we breathe; and neat reviewing 
the different philosophical instruments which assist external observation, 
aan at all times the exact condition and qualities of that mutable 
uid. 
The following mode of proving that the elevation of the at- 
mosphere above the surface of our globe can never exceed a 
certain absolute limit, seems ingenious. 
The highest portions of the atmosphere, which is carried round in twenty 
three hours, and fifty-six minutes, by the rotation of the earth about its 
axis, would be projected into space, if their centrifugal force at that dis- 
tance, were not less than their gravitation towards the centre. But the 
centrifugal force is directly as the distance, while the power of gravity is 
as its square. Consequently, when the centrifugal force at the distance of 
6.6 radii of the earth is augmented as many times, the corresponding gra- 
vitation is diminished by its square, or 43.7 times, their relative proportion 
being thus changed to 289. Now the centrifugal force being only the 289 
part of gravity at the surface of the equator, it will therefore just balance 
this power at the distance of 6.6 radii from the centre, or at the elevation 
of 22,000 miles *. 
It ig equally curious and satisfactory that Dr. Wollaston, in 
his elegant memoir on the finite extent of the atmosphere, by a 
totally distinct train of investigation and research has come to 
nearly the same conclusion. ‘“ But if air consist of any ulti- 
mate particles no longer divisible, then must expansion of the 
medium composed of them cease at that distance where the 
force of gravity downwards upon a single particle is equal to the 
resistance arising from the repulsive force of the mediumt”. 
And again, “ All the phenomena accord entirely with the sup- 
position that the earth’s atmosphere is of finite extent, limited by 
the weight of ultimate atoms of definite magnitude, no longer 
divisible by repulsion of their parts}.” Mr. Leslie, however, 
somewhat inconsistently draws another inference from his cal- 
culations, which Dr.“Wollaston’s researches will not suffer us 
to admit: ‘Perhaps the fluiditself,” says the Professor, ‘‘ may 
* Page 325.-. + Phil. Trans. for 1822, part ist. p.90. + Ibid. p. 98. 
