we are to start upon a journey far beyond the solar system, where shall be our first resting-place? Alpha Centauri is the nearest of the stars whose distance has been well determined; but with all the spiritual swiftness of light, we can reach it only in three years and a quarter. We are separated from the planets by an interval that may be compared to the breadth of a river; but an expanse like the Atlantic Ocean, separates us from the nearest of the fixed stars. The smallest stars visible to the naked eye can probably be reached by a ray of light only in about fourteen years; and the smallest stars, visible in the largest reflectors, would probably require a journey of four thousand years.
Let us now start from the star on which we have gained a footing, for a position from which we may look down upon the group of fixed stars to which our sun belongs. Having gained this position, we find that the sun is part of the Milky Way, which lies like a bright ring before us, with perhaps a tendency to the spiral structure; the cleft in the galaxy corresponding to a coil of the spiral. To expand this ring to its true dimensions, we must remember that a ray of light would probably take a thousand years to speed across its whole breadth. But from our position we find that the Milky Way, with its millions of stars is not the only luminous disc. The whole heavens are studded over with similar patches of light or nebulse which, on closer inspection, are found to be
