Page:In the high heavens.djvu/30

 point may be identified. It can be speedily picked up in the heavens, as follows: Every owner of a telescope is acquainted with Beta Cygni, the most glorious coloured double star that the northern heavens have to offer. A line from Vega to Beta Cygni shows at about one-fourth of the way a bright star, which is Delta Lyrae. It is towards this particular spot of the heavens that the sun, bearing the earth and all the other planets with it, is hurrying at this moment.

The sweep of the solar system through space is represented in the adjoining figure (Fig. 2). The sketch may serve to illustrate the principles on which the determination of the solar velocity is based, but of course it is out of the question that the proper proportions could be observed in such a diagram. In the course of a century the advance of the system towards Lyra will make the stars appear to move in the manner represented by the arrows affixed thereto. Two of the stars are thus seen to spread away from Lyra, while the positions of the other stars are such that they seem to draw in towards the opposite point of the celestial sphere, which is sufficiently indicated by the star Pi Puppis.

If the region to which the motion of our system is directed be adorned by the splendour of Lyra, it is noteworthy that the opposite part of the sphere from which we seem to be flying is also remarkable for its stellar glories. It lies almost midway between Sirius and Canopus.

We shall now turn to the investigation of the allied problem as to the velocity with which the solar system wends its way. A different method of studying the subject which has lately come into practical application