LET. XXII.

SUN AND MOOV.

381

in one of those points, it is plain that there maybe no eclipse, either of the sun or moon, in thespace of several months.

When the nodes, or two points of intersection,are in a right line with the center of the sun, atthe time of a new moon, the moon’s shadowwill fall upon the earth, and occasion a solareclipse; and if they have the same situation atthe time of a full moon, the earth’s shadow willfall upon the moon, and occasion a lunar eclipse.But when the sun and moon are more than se-venteen degrees from either of the nodes at thetime of conjunction, the moon is then generallytoo high or too low in her orbit for any part ofher shadow to fall upon the earth. And whenthe sun is more than twelve degrees from eitherof the nodes, at the time of opposition, themoon is commonly too high or too low in herorbit to go through any part of the earth’s sha-dow ; so that in both these cases there will be noeclipse.

But when the moon is less than seventeen de-grees from either of the nodes at the time ofconjunction, a greater or less portion of hershadow will fall upon the earth as she is moreor less within this limit: and when she is lessthan twelve degrees from the node, at the timeof opposition, she will go through a greater orless portion of the earth’s shadow according to. her situation. And as the fun commonly passes

by