Let us pause here for a moment to think what we have done. Light, travelling with its enormous velocity, requires on an average considerably over ten years to traverse the distance between our Solar System and Stars of the first magnitude, but the dimensions of the Milky Way are built up on such a huge scale that to traverse the whole stratum would require us to pass about 500 stars, separated from each other by this same tremendous interval; 10,000 years may therefore be computed as the shortest time which light, travelling with its enormous velocity, would take to sweep across the whole cluster, it being borne in mind that the Solar System is supposed to be located not far from the centre of this great star cluster, and that the cluster comprises all stars visible arrayed in a flat zone, the edges of which, where the stratum is deepest, being the locality of the Milky Way. Let us once more continue our journey. We have traversed a distance which even on the wings of light we could only accomplish in many thousands of years, and now stand on the outskirts of our great star cluster, in the same way, and I hope with the same aspirations, as when we paused the last time on the confines of our Solar System. Behind us are myriads of shining orbs, in such countless numbers that human thought cannot even suggest a limit, and yet each of these is a mighty globe like our Sun, the centre of a planetary system, dispensing light and heat under conditions similar to what we are accustomed to here. Let us, however, turn our face away from these clusterings of mighty suns, and look steadfastly forward into the unbroken darkness, and once more brace our nerves to face that terrible phantom--_Immensity_. We require now the most powerful instruments that science can put into our hands, and by their aid we will again essay to make another stride towards the appreciation of our subject. In what, to the unaided eye, was unbroken darkness, the telescope now enables us to discern a number of luminous points of haze, and towards one of these we continue our journey. The myriads of suns in our great star cluster are soon being left far behind; they shrink together, resolve themselves into haze, until the once glorious universe of countless millions of suns has dwindled down to a mere point of light, almost invisible to the naked eye. But look forward: the luminous cloud to which we are urging our flight has expanded, until what, at one time, was a mere patch of brightness, has now swelled into a mighty star cluster; myriads of suns burst into sight--we have traversed a distance which even on the wings of light would take hundreds of thousands of years, and have reached the confines of another Milky Way as glorious and mighty as the one we have left; whose limits light would require 10,000 years to traverse; and yet, in whatever direction the telescope is placed, star clusters are to be seen strewn over the surface of the heavens.