88 J. L. Stockwell on secular variation in the Earth's Orbit. | 
data for determining the secular variation of the climated | 
either hemisphere of the earth. It would be necessary, iit 
this purpose, to take into account the secular variation of th 
precession of the equinoxes, and also of the obliquity of the 
ecliptic to the terrestrial equator, in order to determine the ob | 
liquity and intensity of the sun’s rays on any given latitudedt 
the earth’s surface. But so far as the earth as a whole is coh 
cerned, the only element which it is necessary to take into at 
count, is the eccentricity of the orbit. And the values of this 
element are given in the following table, at intervals of tet | 
thousand years, together with the longitude of the perihelion 
of oe earth’s orbit. t 
: Int e Treatise on Secular Equations, &c., already referred 
: of oe poke given a table and chart, showing the eccentricilY 
and chart here given, are merely an extensio? 
and chart, over a preceding million of ee 
r iod 0 
