At the time of Struve’s investigation Mädler, at Dorpat, was engaged in an attempt to solve the question of the construction of the heavens by quite another method, that of stellar proper motion. He determined to investigate the subject of proper motion in order to discover the central body of the Milky Way. If such a centre existed, however, the motions near it would be somewhat different from those in the Solar System. In our Solar System the planets nearest the Sun move swiftest, owing to the strength of the force of gravitation. In the Sidereal System, on the other hand, the movements at the centre, as Mädler pointed out, would be slowest. As there would be no very large preponderating body, the mutual attractions of the different stars would cause the bodies at the boundaries of the Universe to move faster than those at the centre, the central sun—the object of Mädler’s search—being in a state of rest relative to the Sidereal System. Mädler accordingly began to search the heavens for a region of sluggish proper motions. In the constellation Taurus, Mädler noticed that the proper motions of the stars were very slow. The idea occurred to him that the bright red star Aldebaran might be the central sun, but its very large proper motion was obviously against this inference. Star after star was now subjected by Mädler to the most careful scrutiny. At length, after a laborious investigation, he announced that the star which fulfilled the conditions of a central body was Alcyone, the brightest of the Pleiades, a group possessed of no proper motion except that due to the sun’s drift in the opposite direction. In 1846 Mädler published his hypothesis in his elaborate work, ‘The Central Sun.’ He announced that his observations had led him to the conclusion that Alcyone occupied the centre of gravity of the Sidereal System, and was the point round which the stars of the Galaxy were all revolving. His profound imagination, however, did not stop here. This speculation led him to the sublime thought that the centre of the Universe was the Abode of the Creator. In 1847 Struve rejected Mädler’s theory as “much too hazardous,” and this has been the general opinion of astronomers. Mädler’s theory is now regarded as quite untenable.