"At the present time we employ a for making certain observations which can best be made then, and for other work which is not possible at another time. The most important work, and one which demands the coöperation of at widely distant places, is the observation of s. These occur at other times, but only the brighter stars can be followed to the and such stars are not frequent in its path. During an eclipse, however, stars down to the eleventh are easily followed until they disappear, and any star whose position is accurately determned is available. If an Observatory has undertaken the investigation of the Moon's place, it takes advantage of a total eclipse and prepares a list of stars which are to be occulted at other distant observatoreis, and sends a circular requesting observations. Such a circular was issued by the , Russia, for the eclipse of March 10th. The time of an occultation is much less difficult to determine than a contact of an eclipse. The Moon has no atmosphere, so that the star disappears instantaneously."