Ileer — Miocene Flora of the Polar Regions. 279 



summer was cooler, and the short winter on the other hand was 

 warmer. The astronomer, Mr. Stones, has calculated that 850,000 

 years ago the eccentricity of the earth's orbit was at its maximum, 

 and the northern hemisphere had the winter in aphelion. At that 

 time the length of the winter was increased by thirty-six days. Very 

 much ice and snow must have accumulated in this period, and con- 

 sequently Lyell is inclined to consider this as the Glacial age. On the 

 other hand, 900,000 years ago the eccentricity was at its minimum,and 

 consequently other data must be given for the conditions of climate. 



But with respect to all these speculations, we must bear in mind 

 the insufficiency of our knowledge as to the effect which the distance 

 travelled by the sun's rays from the sun to the earth has on their 

 intensity. Lyell has very justly drawn attention to the fact, that, 

 according to the calculations of Dove, the earth is warmer in July, 

 when it is actually further from the sun, than in December, when it 

 is nearest to it. This arises from the different distribution of land 

 and water in the southern and northern hemispheres, so that the latter 

 has a warmer summer than the former, although in the summer the 

 sun is nearer to the south than the north. But even this shows, that 

 the distribution of land and sea on the earth is of much greater im- 

 portance, in a question of climate, than the greater or smaller 

 eccentricity of the earth's orbit, which ought not therefore to have 

 Buch an excessive influence ascribed to it. Still, it is an item by no 

 means to be neglected, and one which, combined with varied dis- 

 tributions of land and sea, must exercise a great influence. Sir 

 Chas. Lyell has demonstrated this in a most masterly manner. 



A second cosmical agent for changes of climate may be looked for 

 in the sun itself. With respect to the spots on the sun's disc, we 

 know that perpetual changes are going on upon the surface of the 

 sun, so that there is at least a possibility that the action of the sun's 

 rays may not always have been the same. 



But, besides the sun, there are also in the universe millions of 

 heavenly bodies, pouring out their lightening and warming rays into 

 the firmament. It is, therefore, possible, that different places in this 

 infinite universe may possess a diff'erent temperature, as has been 

 pointed out by the mathematician Poisson, who reminds us that the 

 number of stars is so great that they form, as it were, a continuous 

 covering over us. 



Now, we know that the sun, together with its planets, is continu- 

 ally changing its place in the universe ; and, probably, together with 

 them, is circling round some one great fixed star at an immeasurable 

 distance. If we consequently venture to suppose that the universe 

 has not everywhere the same temperature, we should have the most 

 simple explanation of the phenomena we have described. If the 

 sun, with its planets, was, in the Miocene times, in a part of the 

 universe possessing a higher temperature than that in which it now 

 moves, this warmth would have been proportionabty shared by every 

 part of the earth, and would more especially have had an influence 

 on the temperate and polar zones, and have caused a proportionate 

 increase of temperature. Then, again, in this year of our sun (if it 



