thankful that our eyes have the imperfection of not appreciating parallel rays. But we will now consider how this imperfection may be remedied by science. There are two different ways of doing this--viz., first, by increasing the amount of light received, by means of telescopes of great aperture; and secondly, by employing an artificial retina a thousand times more sensitive than the human. Now, the human retina receives the impression of what it looks at in a very minute fraction of a second, provided of course that the eye is properly focussed, and no further impression will be made by keeping the eye fixed on that object; but in celestial photography, when the telescope is turned into a camera, the sensitive plate, having received the impression in the first second, may be exposed not only for many seconds, or minutes, or hours, but for an aggregate of even days by re-exposure, every second of which time details on that plate new objects, sunk so deep in the vast depths of space as to be immeasurably beyond the power of the human eye, even through telescopes hundreds of times more powerful than the largest instruments that science has enabled us to construct; and yet here is laid before us a faithful chart, by means of which we may once more continue our journey through space. A short exposure will show us firmaments and nebulae just outside the range of our greatest telescopes, and every additional second extends our vision by such vast increases of distances that the brain reels at the thought; and yet, as we have seen, exposures of these sensitive plates may be, and have been, made not only for seconds, but for thousands and even hundreds of thousands of seconds! And still there is no end, no end where the weary mind can rest and contemplate; the finite mind of man can only cry out that there is no limit. In spite of all its strivings and groping by aid of speculative philosophy, the finite cannot attain to the Infinite, nor get any nearer to where the mighty sea of time breaks in noiseless waves on the dim shore of eternity.