294 



DATES OF THE VARIATIONS IN 



[Ch. XIII 



by Mr. John Carrick Moore, gives in millions of miles the difference between the 

 greatest and least distances of the earth from the sun, during the excentri cities 

 given in column Z. 



Column 4. Gives the number of days by which winter occurring in aphelion is 

 longer than the summer in perihelion. 



Column 5. Gives the mean temperature of the hottest summer month in the 

 latitude of London when the summer occurs in perihelion. 



Column 6. Gives the mean temperature of the coldest winter month in the 

 latitude of London when the winter occurs in aphelion.* 













tricity. For in A it was nearly three times 



at present ; 



tl 







periods, one three and a half and the other four and a 

 half times as great, with an intervening smaller excen- 

 trieity ; and lastly in the period D, more than three times the 

 present excentricity. If we could be sure that the greatest 



miles 



13i 



millions, was sufficient 

 much bevond those whicl 



would occasion, we can hardly refuse to infer that the other 



mao 



would have left 



their refrigerating influence. 



b 



The periods of A and B would 



sufficiently 



time for that series of glacial and post-glacial events which 

 we can prove to have happened since the epoch of the greatest 

 cold. These events relate to changes in the level of the land in 

 opposite directions, as well as the excavation of valleys, and 

 variations in the range and distribution of aquatic and terres- 



animals 



sufficient 



of changes with which we are acquainted. I agree, therefore 



and similarly the temperature of the 

 hottest northern summer month in 



1-0168 



1 



* Supposing the mean temperature 

 of the hottest and coldest months at 

 London to he 64° F. and 38° F., respec- perihelion from the formula 

 lively, and the temperature of space to be 

 — 239° F., the present excentricity being 

 0*0168, and the north winter occurring 

 in perihelion, then the temperature (t) 

 of the coldest northern winter month 

 when in aphelion for excentricity (e) 

 will be found from this equation 



239° + £ 

 236° + 64° 



e 



239° + * 

 239°~^8° 



0- 9832 

 1 -I- e 



Sir John Leslie and Mr. Traill give 

 64°-67, and Dove 63°*08, for the tempe- 

 rature of the hottest month in the 

 latitude of London. 



The above results must be taken as 

 mere rough approximations. 



