122 HEAT OF EARTH'S OUTER CRUST. 



the year fall on the average about the middle of 

 January. 



In the higher latitudes the proportional diminu- 

 tion of the heating power of the sun is compen- 

 sated, to a great extent during the summer months, 

 by its longer stay above the horizon; and thus, 

 not only in the temperate zones, but even within 

 the polar circle, a warm though brief summer is 

 ensured. 



The three months, June, July, and August, cor- 

 respond pretty nearly with the summer in the 

 whole of the northern hemisphere, and with the 

 winter in the southern. During our autumnal 

 months, September, October, November, spring 

 reigns in the southern hemisphere. The season that 

 is coldest on the average, or the winter, of the north, 

 falls in the months December, January, and Febru- 

 ary, which are the summer months of the south. 

 Lastly, the spring of the one-half of the globe, 

 and the autumn of the other, are represented by 

 the months March, April, and May. 



The preceding considerations will give you but 

 a very general notion of the conditions of climate 

 at different points of the earth's surface, since these 

 conditions are everywhere, and especially in the 

 extra-tropical regions, modified by local causes, 

 and by variations in the state of the atmosphere. 

 The true relations of the temperature of one district 

 cannot therefore be deduced from those of another, 



