ABSTRACT
The method of measuring the distance of some of the stars will be better understood. Halley was the first to prove that some of the stars had really independent or “proper” motions, which he ascertained by comparing their positions with those given by earlier observers. Arcturus was thus found to be moving at the rate of two seconds a year, and two other bright stars, Sirius and Aldebaran, had similar motions. It was only in the nineteenth century that the proper motions of a considerable number of the stars were accurately determined, and that it became possible to attack the far more difficult problem of the distances of the stars with any prospect of success. The proper motion of the stars has given astronomers a guide to those which are probably nearest to us, and which, therefore, can be most easily measured, and the method of measurement must be indicated.
