Lesson xxxin.] SEASONS. 223 



During the short days, the sun's influence it 

 less, both with respect to the intensity of its rays 

 and the time of their continuance, which there- 

 fore produces \yinter: during the long days, it is 

 greater in both respects, and therefore causes 

 Summer. The middle seasons of Spring and Au- 

 tumn correspond with the equality of nights and 

 days. It is to be remarked, however, that this 

 correspondence is not perfectly exact ; for the 

 severest frosts usually take place afier the days 

 hare begun to lengthen, and the most oppres- 

 sive heats are found to happen when the days 

 are decreasing : the reason of which is, that the 

 earth, having imbibed more heat than it gave out 

 during the summer months, is not exhausted of 

 its superabundant warmth till about the close of 

 the year: in like manner, because the waste 

 of the earth's heat is greater in Winter than 

 its supply, it continues to imbibe heat during 

 the Spring, and is not saturated till after the 

 Summer Solstice. Hence also arises the differ- 

 ence between the Spring and Autumn, though 

 the position of the sun,, in respect to the earth, is 

 in both the same. The heat, "of- the Spring is 

 inferior to that of Autumn, both in point of 

 regularity and degree; for, on account of the 

 deficiency of warmth in the earth, it is con- 

 stantly imbibing heat from the lower part of 

 the atmosphere; hence originates a large collec- 

 tion of cloud.-?, which, intercepting the solar 

 rays, combines, together with the absorption of 

 the earth, to .deprive the air of much of its heat: 

 L.4 whereas 



