J. L. Stockwell on secular variation in the Earth’s Orbit. 89 
1850; the line XX’, in like manner, shows the mean value 
of the eccentricity, or, in other words, the square root of the 
non-periodic term in the expression of the square of the ec- 
minima are approximately repeated at intervals of 1,450,000 
years, In other words, if at any epoch, there is a maxima or 
minima of any given magnitude, in 1,450,000 years before or 
after that epoch, there will be a corresponding maxima or 
n eferring to the charts for a particular example, we 
notice that for the abscissa —77, there is a very large maxima, 
and equal to 0-066 nearly ; and if we add 145 units of ab- 
scissa to -77, we get +68, and for this abscissa the correspond- 
ing ordinate, or the eccentricity, is equal to 0-058. The maxi- 
was oe by Croll a few years ago, and was derived from 
Le errier’s formula, But the intervals used in his computa- 
tion were much too long, being 50,000 years, instead of 10,000 
have used in our computation. It is evident, 
at the following — 
ep 
