H6 SECULAR VARIATIONS OF THE ELEMENTS OF 



49'.27. The present length of the tropical year is 365 d 5" 48 m 47 8 .26. Whence 



we get 



maximum length of tropical year =365" 5 h 49 m 36 9 .53; 

 and minimum length of tropical year =365 5 47 48.13. 



Lastly, if we take the sum of the coefficients of the sines in the formula for - , 



we shall find that the annual variation of the obliquity is always confined within 



the limits of 



0" and 0".744167. 



