224 Royal Society. 



mal state, several inflections ; and its character depends materially 

 on the elevation of the point of observation. 



3. The approximations to the value of extra- atmospheric radia- 

 tion, on the hypothesis of a geometrical diminution of intensity, are 

 inaccurate. 



4. The tendency to absorption through increasing thicknesses of 

 air is a diminishing one ; and in point of fact, the absorption almost 

 certainly reaches a limit beyond which no further loss will take 

 place by an increased thickness of similar atmospheric ingredients. 

 The residual heat, tested by the absorption into a blue liquor, may 

 amount to between half and a third of that which reaches the sur- 

 face of the earth after a vertical transmission through a clear at- 

 mosphere. 



5. The law of absorption in a clear and dry atmosphere, equiva- 

 lent to between one and four thicknesses of the mass of air traversed 

 vertically, may be represented, within those limits, by an intensity 

 diminishing in a geometrical progression, having for its limit the 

 value already mentioned. Hence the amount of vertical transmis- 

 sion has always, hitherto, been greatly overrated ; or the value of 

 extra-atmospheric solar radiation greatly underrated. 



6. The value of extra-atmospheric solar radiation, on the hypo- 

 thesis of the above law being generally true, is 73° of the actino- 

 meter marked B 2. The limiting value of the solar radiation, after 

 passing through an indefinite atmospheric thickness, is 15° 2'. 



1. The absorption, in passing through a vertical atmosphere of 

 760 millimeters of mercury, is such as to reduce the incident heat 

 from 1 to 0-534. 



8. The physical cause of this law of absorption appears to be 

 the non-homogeneity of the incident rays of heat, which, parting 

 with their more absorbable elements, become continually more per- 

 sistent in their character ; as Lambert and others have shown to 

 take place, when plates of glass are interposed between a source of 

 heat and a thermometer. 



9. Treating the observations on Bouguer's hypothesis of a uniform 

 rate of extinction to the intensity of the incident rays, the author 

 obtains for the value of the vertically transmitted shares of solar 

 heat in the entire atmosphere, — 



By the relative intensities at Brientz and the Faulhorn... 0*6842 

 By the observations at the Faulhorn alone, — 



First method 0*6848 



Second method 0*7544 



By the observations at Brientz alone, — 



First method 0*7602 ' 



Second method 0*7827 



June 9. — A paper was read, entitled, " On the Specific Inductive 

 Capacities of certain Electric Substances." By William Snow Har- 

 ris, Esq., F.R.S. 



The author, pursuing the experimental inquiry suggested by the 

 theory of Mr. Faraday relative to the differences in specific induc- 

 tive capacity exhibited by different dialectric substances, instituted 



