Excerpt from The Solar System, Illustrated by the GeoseleneanThe object of this arrangement is to give the true position of the earth's axis and to show not only day, night, the seasons, etc, but also the recession of the equinoxes and its effects. The number of the teeth of the wheel P is proportioned relatively to those of the wheels which ao tuate it, and for instruments of moderate size the wheels L and M may have one-fourth as many teeth as H has, while P has one tooth less than H, to obtain a slow rotation of the wheel P relatively to the sun. The small wheel S aids in obtaining this result by reversing the direction of the rotation of the wheel P.At the outer end of the sleeve J beyond the wheel M formerly men tinned are two wheels N and O, the former of which gears into the spur wheel Q, which rotates upon and independently of the inner sleeve to which the moon-carrier is attached. On the outer sleeve there is an oh lique circular plane forming a track for the roller of the moon-carrier. The revolution of the wheel Q with the oblique plane preserves the moon's orbit in its true position in reference to the orbit of the earth. The pro portion of the number of teeth in the wheels N and Q is such that Q makes about one-eighteenth of a revolution in the period of a year and thus shows the recession of the moon's nodes and regulates the phenomena of solar and lunar eclipses.The crown-wheel R is attached to the upper end of an inner sleeve and is revolved with it by means of the gear-wheel O, on the end of the sleeve J which wheel meshes into a horizontal wheel and this again into a pinion on the inner sleeve. These two wheels are under the wheel Q and are concealed.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.