At the present day we look upon these wonderful events as the results of natural causes, whose operations have long since been explained. We have learned that an eclipse of the sun is merely the moon coming between the earth and the sun, thus shutting off from the former all or a portion of the light of the latter; that this event may occur as often as five times, and never less than twice in one year; that it can only occur at time of new moon; that it occurs only in limited portions of the earth at any one time, and hence, that although happening so often, for any given place it is a comparatively rare event—especially the last two of the three kinds, _partial_, _annular_, and _total_; and that the portion of the earth affected by a total eclipse does not exceed 170 miles in diameter; or, in other words, the width of the moon’s shadow, when it falls perpendicularly on the earth’s surface, is not more than 170 miles. We have learned, also, that an eclipse of the moon is occasioned by the earth coming between the moon and the sun; that this event can not occur more than twice in any one year, and may not occur even once; that it happens always at full moon; that it can be seen in all parts of the earth where the moon is above the horizon at the time of the occurrence; and for this reason, although it only happens in the ratio of 29 to 41 as compared with eclipses of the sun, yet there are more lunar than solar eclipses visible in any given place. During the present month we shall have two eclipses, one of the sun and one of the moon. THE SUN