studded with continents and islands of stars, which he called nebulæ, clusters, or groups. The Milky Way, with its many millions of shining suns, is one of these thickly peopled islands, separated from many others as rich or perhaps richer of worlds, in this infinite ocean. Of these nebulæ or clusters, or star islands, he had, up to that time, counted "more than 900, many of which, in all probability, are equally extensive with that which we inhabit; and yet they are all separated from each other by very considerable intervals. Some there are that seem to be double and treble; and though with most of these it may be that they are at a very great distance from each other, yet we allow that some such conjunctions really are to be found. But then these compound or double nebulæ still make a detached link in the great chain." He fell from some of these views at a later period, wholly or in part.
Herschel delighted in these attractive speculations. In a paper on the power of telescopes to penetrate space, one of the conclusions he came to was that, while his 20-feet reflector "might possibly have reached to some distance beyond the apparent bounds of the Milky Way," his 40-feet would reach stars from which light would take about two millions of years to reach our earth. A ray of light revealing to us the history of stars as it was two millions of years ago! If such things are dreams or miscalculations, they soar into the sublimest regions of mortal thought. More amenable to arithmetic is his calculation, that it will require not less than 598 years, of 100 working hours each, to take a census of the stars by looking with his 40-feet "only one single moment into each part of space, and, even then, so much of the southern
