Page 100 - 89 history of astronomy_opt
P. 100
1693, compared this value with his own mea-
surements, and so discovered the acceler-
ation of the moon’s mean motion. This
was conclusively established, but could not
be explained by the Newtonian theory for
quite a long time.] He determined the plane
of the moon’s orbit and its inclination to the
ecliptic. The motion of this plane round the
pole of the ecliptic once in eighteen years
100
