by displacement of the lines of the spectrum); the star No. 1830, of Groombridge's catalogue (see "In the High Heavens"), has a rate of two hundred miles per second. The author says, "Indeed, in some cases stellar velocities are attained which appear to be even greater than that just mentioned. We do not, therefore, make any extravagant supposition in adopting a speed of twenty miles per second," which he takes as the average. "I have adopted this particular velocity as fairly typical of sidereal motions generally. It is rather larger than the speed with which the earth moves in its orbit." The distances, of course, are equally enormous. This author says, "The nearest star, as far as we yet know, in the northern hemisphere is 61 Cygni.... I think we cannot be far wrong in adopting a value of fifty millions of millions of miles.... In the course of a million years a star with the average speed of twenty miles a second would move over a distance which was about a dozen times as great as the distance between 61 Cygni and the solar system." This assuming that the solar system is at rest, which is not the case, as the author says, "Unless binary, stars do not remain in proximity, so far as we know; the general rule appears to be that of universal movement through space." This drift through space, however, no more affects the terms of the problem than the rotation of the earth upon its axis or its orbital motion affects the operations of an electric machine as the handle may be rotated to or from the direction of these motions. Both machine and reservoir of energy occupying a fixed relation with reference to each other, the positions of each are the same as though absolutely fixed. This is true of gravitation, likewise, as well as of all other natural and universal forces.