Note 50 — CHAP. IX. The Method of finding the Distances of the Sun, Moon, and Planets.
Reading edition
By this is meant, that if a line be supposed to be drawn parallel to the Earth’s Axis in any part of it’s Orbit, the Axis keeps parallel to that line in every other part of it’s Orbit: as in Fig. I. of Plate V; where abcdefgh represents the Earth’s Orbit in an oblique view, and Ns the Earth’s Axis keeping always parallel to the line MN.