The Harvard Observatory is now making a specialty of the study of the movement of the stars. The question which Observatory astronomers are seeking to settle is: Why do the stars move, and what natural law if any gives them a goal and a rate of speed?

As the cast of each of 50,000 different stars must be studied before conclusions can be drawn, and as in order to do this 2,000 plates must be examined minutely, the problem is a most difficult one. The difficulty is increased by the fact that the stars move so slowly that it is a long time before any two plates of the same portion of sky can be compared.

The University has been a leader in the work of photographing the stars. After the first plates were made in 1888; ten years then elapsed before other observatories took up the work seriously. The collection of about 400,000 plates which the University has amassed forms the backbone of the University Observatory. If a new star is discovered, news of its discovery is first telegraphed to Cambridge: for the records there, which have note of everything that has happened in the sky during the last 20 years, are the most complete in the world. One reason the Harvard collection of plates is so valuable is that it contains a map of the whole sky as it appeared 30 years ago.

The University Observatory, which produces 10,000 plates a year, is now under the direction of Professor Harlowe Shapley. W. J. Luyten is carrying out the study of moving stars. Two stations for observation are maintained--one at Cambridge for the study of the northern hemisphere and one at Bloemfontein, South Africa, for the study of the southern hemisphere.