158 COSMICAL ARRANGEMENTS. 



judge, the only one which would answer the pur- 

 pose of the earth, perhaps of the other planets, 

 as the seat of animal and vegetable life. If the 

 earth's orbit were more excentric, as it is called, 

 if for instance the greatest and least distances 

 were as three to one, the inequality of heat at 

 two seasons of the year would be destructive to 

 the existing species of living creatures. A cir- 

 cular, or nearly circular, orbit, is the only case in 

 which we can have a course of seasons such as 

 we have at present, the only case in which the 

 climates of the northern and southern hemispheres 

 are nearly the same ; and what is more clearly 

 important, the only case in which the character 

 of the seasons would not vary from century to 

 century. For if the excentricity of the earth's 

 orbit were considerable, the difference of heat at 

 different seasons, arising from the different dis- 

 tances of the sun, would be combined with the 

 difference, now the only considerable one, which 

 depends on the position of the earth's axis. And 

 as by the motion of the perihelion, or place of the 

 nearest distance of the earth to the sun, this 

 nearest distance would fall in different ages at 

 different parts of the year, the whole distribution 

 of heat through the year would thus be gradually 

 subverted. The summer and winter of the tropical 

 year, as we have it now* being combined with the 

 heat and cold of the anomalistic year, a period of 

 different length, the difference of the two seasons 



