454 Analt/ses of Books.- [Dec. 



the Atmosphere.'* 4. " On the Horary Oscillations of the 

 Barometer.'* 5. " On the Climate of London." To these are 

 added a collection of meteorological observations in tropical 

 climates by Capt. Sabine and Mr. Caldcleugh ; some remarks on 

 the barometer and thermometer ; observations upon heights ; 

 and a meteorological journal of three years kept by Mr. Daniell. 

 The first essay, which treats of the constitution of the atmo- 

 sphere, is divided into four parts. Under the first are considered 

 the habitudes of an atmosphere, of a perfectly dry and perma- 

 nently elastic fluid ; in the second those of an atmosphere of 

 pure aqueous vapour ; in the third, the compound relations of -a 

 mixture of the two ; and in the fourth, the principles which have 

 been derived from these inquiries are apphed to the phenomena 

 of the mixed atmosphere of the earth. 



After recapitulating those statical laws of elastic fluids which 

 were first developed by Newton, Mr. Daniell proceeds to calcu- 

 late the influence of temperature in modifying the density and 

 elasticity of air at different elevations. The principle from 

 which the necessary data are derived was pointed out originally 

 by Mr. Dalton in his " New System of Cnemical Philosophy," 

 Part I. p. 128. It is there conjectured, that "the natural equi- 

 librium of heat in an atmosphere is when each atom of air, in the 

 same perpendicular column, is possessed of the same quantity of 

 heat ; and consequently, owing to the increased capacity pro- 

 duced by rarefaction, the natural equihbrium of heat is when the 

 temperature gradually diminishes in ascending." The formula, 

 however, on which the calculations of Mr. Daniell are founded, 

 was furnished by Prof. Leslie. But it may be reasonably 

 doubted, whether the experimental process of which this for- 

 mula expresses analytically the result, be susceptible of the 

 necessary accuracy. 



Hitherto the temperature of the sphere round which this 

 imaginary atmosphere is diffused, has been supposed to be 

 unirormly the same on every part of its surface. The hypothesis 

 is now, however, to be changed ; and we are to contemplate a 

 sphere the temperature of which being 0° Fahr. at the poles, 

 increases &y equal degrees till it becomes 80° at the equator. 

 From this supposition, the conclusion immediately follows, that 

 the atmospheric column over the polar regions will be shorter 

 and denser than that over the equator ; and consequently that 

 an inferior current of cold air will flow uniformly from the poles 

 to the equator. At a certain elevation, the greater density of the 

 polar air will be exactly counterbalanced by the greater elasti- 

 city of the equatorial ; and of this equilibrium of forces, perfect 

 rest must necessarily be the result. Above this quiescent point, 

 a current in the opposite direction, viz. from the equator to the 

 poles, will manifestly be established. This constant and regular 

 flow, according to Mr. Daniell, modifies in no respect the height 

 of the mercurial column. 



