The young astronomer in _Two on a Tower_—that bitter-sweet story in which our great novelist Hardy tells of the weird fascination with which the study of the stars appeals to a sensitive nature, exclaims: “The imaginary picture of the sky as the concavity of a dome whose base extends from horizon to horizon of our earth, is grand, simply grand, and I wish I had never got beyond looking at it in that way. But the actual sky is a horror.” “There is,” he continues, “a size at which dignity begins; further on there is a size at which grandeur begins; further on there is a size at which solemnity begins; further on a size at which awfulness begins; further on a size at which ghastliness begins. That size faintly approaches the size of the stellar universe.” “If you are cheerful and wish to remain so,” he concludes, “leave the study of astronomy alone. Of all the sciences, it alone deserves the character of the terrible. If, on the other hand, you are restless and anxious about the future, study astronomy at once—your troubles will be reduced amazingly. But your study will reduce them in a singular way, by reducing the importance of everything, so that the science is still terrible, even as a panacea.” The facts revealed by the study of astronomy which have this feature of ghastliness and terror relate to the enormous distances in space at which the stars are placed, and to their enormous number. One may sometimes see on the coast or in some marshland a “pile-driver” at work. At a quarter of a mile distance you can see the great weight hoisted up by cranks and chains above the “pile,” which stands upright but not yet driven very far into the ground. You see the weight let go; it drops vertically on to the pile, and you watch it rising some two or three feet on its return journey upwards, when suddenly you hear the sound of a sharp blow, and only after an effort realise that the sound was made more than a second ago, and that the workmen have had time to raise the weight 3 ft. before the sound travelled to you. Sound travels less than a quarter of a mile in a second. Light also takes time to travel, but it advances ever so much more quickly than sound, namely, 186,000 miles (and a bit more) in a second. It is, therefore, easy to calculate the number of miles traversed by light in a minute or in a year. There are thirty million seconds in a year. The light of the sun takes eight minutes to reach the earth, so, instead of stating the number of miles of this distance, we may say that the sun is eight “light-minutes” distant from the earth (about 89,000,000 miles). This is an enormous figure. The sun and his planets may be represented proportionately by a golden ball a foot in diameter, and a number of little spheres varying in size from that of a dried pea to a boy’s marble, placed at distances from the golden ball varying from 50 ft. to 200 ft. Such a model is shown in the Museum of Practical Geology in Jermyn Street, London.