THEIR ARRANGEMENTS AND FORMATION. 3 which the same inference was to be made in their case. But a sensible parallax of about one second has been ascertained in the case of the double star, a a, of the constellation of the Centaur,* and one of the third of that amount for the double star, 61 Cygni; which gave reason to presume that the distance of the former might be about nineteen millions of millions of miles, and the latter of much greater amount. If we suppose that similar inter vals exist between all the stars, we shall readily see that the space occupied by even the comparatively small number visible to the naked eye must be vast beyond all powers of conception. The number visible to the eye is about three thousand; but when a telescope of small power is directed to the heavens, a great number more come into view, and the number is ever increased in proportion to the increased power of the instru ment. In one place, where they are more thickly sown than elsewhere, Sir William Herschel reck oned that fifty thousand passed over a field of view two degrees in breadth in a single hour. It was first surmised by the ancient philosopher, Democritus, that the faintly white zone which * By the late Mr. Henderson, Professor of Astronomy in the Edinburgh University, and Lieutenant Meadows. B 2
