6 ASTRONOMY. 



Days 



It has been computed that in the year"J 

 1800, from the vernal equinox (the f 

 21st March) to the summer solstice t 

 (the 21st June) was j 



From the summer solstice to the au- 7 

 tumnal equinox (the 21st September) j 



From the autumnal equinox to the win- 

 ter solstice (the 21st December) 



From the winter solstice to the vernal 

 equinox (the 21st March) - 



QQ 



Days, 365-24236 



The spring therefore is now shorter than the sum- 

 mer, and the autumn longer than the winter. 



So long as the solar perigee remains on the side 

 of the equator where it now is, the spring and sum- 

 mer taken together will be longer than the autumn 

 and winter taken together. In the present age the 

 difference is about seven days as appears from the 

 preceding values. These intervals, however, will 

 become equal about A. D. 6485, when the perigee 

 will reach the vernal equinox ; afterwards it will 

 pass beyond it, and the spring and summer taken 

 together will become shorter than the autumn and 

 winter. 



Such phenomena could not obtain if the motion of 

 die sun w r ere circular and uniform, as then all the 

 seasons would be equal. The eccentricity of the 

 orbit therefore, although very small, has a sensible 

 influence on the duration of the seasons, and the 

 displacement of the major axis, though very slow, 

 produces variations which become perceptible in 

 distant ages. 



The Harvest Moon. 

 The year 1818 was the third of a series of ten 



