540 Change of Climate due to Eccentricity of Earth's Orbit. 



line of equinoxes for the year 1800, and are given merely to show 

 the degree of rapidity of change of its position. 



Table. 



Years ago. 



Value of e. 



Longitude of © 

 perihelion. 



170,065 



00437 



228 7 



180,065 



00476 



209 22 



11)0,065 



00532 



190 4 



200,065 



00569 



168 18 



210,085 



00575 



144 55 



220,065 



0-0497 



124 33 



230,065 



00477 



102 49 



I may mention that the above represents the maximum state 

 of the excentricity during the last 500,000 years. 



With respect to the precession of the equinoxes, although it 

 would not be correct to assume the uniformity of motion during 

 the immense periods of time here under consideration (for the 

 accumulative error would become large), it will certainly lead to 

 no sensible error to assume its values at the time 210,065 years 

 ago as not very different from the present one. 



It will be seen from the Table, that the change of excentricity 

 and longitudes of perihelion are exceedingly slow as compared 

 with the motion of the line of equinoxes ; that if Mr. CrolFs 

 theory is correct, we must have had, when the excentricity is 

 larger, alternate changes of climate from one of extreme cold to 

 one of great equability. 



The main point of the argument, as I understand it, of change 

 of climate depending upon the excentricity of the earth is as 

 follows. It is true that the amount of heat received varies but 

 very slightly with changes in the excentricity; but the mean 

 temperatures will depend as much upon the heat radiated off as 

 upon that received ; the amount of heat radiated off will certainly 

 be less the shorter the time the temperature- is below the mean, 

 and the less it sinks below the mean ; hence, ctsteris paribus, a 

 warm winter and a short one must raise the mean temperature, 

 and a cold winter and a long one must lower this mean (the 

 mean temperature) . The effects produced, however, are terribly 

 involved. 



I have the honour to be, Sir, 



Your obedient Servant, 



E. J. Stone. 



