We elevate the ice-block in front of the lamp, so that the light may now pass through its substance. Compare the ray as it enters with the ray as it makes its exit; to the eye there is no perceptible difference, and its intensity seems scarcely diminished. But not so with its heat. As a thermic agent, the ray was more powerful before its entrance than it was after its emergence. A portion of its heat is arrested, is detained in the ice, and of this portion we now proceed to avail ourselves. What will it effect? We place a lens in front of the ice upon the screen. Now, observe this image (see Illustration), the beauty of which is still very far from the real effect. Here is one star; yonder is another; and in proportion as the action continues, the ice appears to resolve itself more and more into stars, all of six rays, like snow-crystals, and resembling a beautiful flower. By moving the lens in and out, we bring new stars into sight; and while the action continues, the edge of the petals is covered with indentations like those of the leaf of a fern. Probably, few of our readers have any conception of the magical beauties concealed in a block of ice! Let them remember that prodigal Nature works in this way throughout the whole world. Every atom of the solid crust which covers the frozen waters of the North, has been wrought out in obedience to the law we have enunciated. Nature is always and everywhere harmonious; and it is the mission of Science to awaken us to an appreciation of its concords. [Illustration: EXHIBITION OF ICE-FLOWERS BY PROJECTION.] [Illustration: ICE-FLOWERS.] There is another point of our experiment to which the reader’s attention must be directed. He sees the flowers illuminated by the ray which traverses them. But if he examines them, while turning upon them a ray which they will reflect and send back to his own eye, he will see in the centre of each a spot with the brightness of burnished silver. He will be tempted to think that this spot is a bubble of air; but, by immersing the ice in hot water, you can melt the ice all around the spot,--and when it alone remains, you will see it diminish and disappear without any trace of air. The spot is a vacuum. Such is the faithfulness to herself with which Nature operates; thus, in all her operations, does she submit to her own laws. We know that ice, in melting, contracts; and here we arrest the contraction, as it were, in the very act. The water of the flowers cannot fill the space occupied by the ice which by its fusion has given birth to them; hence the production of a vacuum, the inseparable companion of each liquid flower.