As I have discussed this question elsewhere and touched on it in other chapters, extended discussion might cause repetition. Besides, this volume is not intended for detail or abtruse minutiæ, but for the statement of leading facts for the masses of intelligent people, who abhor technical terms and dry details. Many people find scientific books so dry and unpalatable, that, like the weary listener to the dry, dull sermon of the missionary, who said: "If I were a cannibal from Timbuctoo, I would eat that missionary and his hymnbook too." Doubtless he thought the hymnbook would be excellent dessert after such a dry meal; and some readers of scientific works find most any kind of dessert refreshing after partaking of the mental pabulum of dry statistics and technical terms to be found in many scientific works. Our American Indian is never dull or unpoetic in his conception of the Universe. He sees God in the lightning, hears Him in the thunder; and according to him the "Milky Way" is the "Path of souls" leading to the villages in the sun. Along this pathway travel the spirits of the dead, and the brighter stars are "the campfires for the solitary journey to the land of the hereafter." The Japanese term the Milky Way "the silver river of heaven." And the ancient Greeks considered the blue dome of the sky a crystal globe where dwelt the Olympian gods. No science should be dry, and above all astronomy should lift us to empyrean heights where we may tread among the stars. CHAPTER VIII RECENT ELECTRICAL DISCOVERIES AND APPLIANCES, WIRELESS TELEGRAPHY, ETC. It is said facts are now being discovered and physical theories developed the ultimate result of which may be the explanation of the mysterious phenomena presented by the corona of the sun, the tails of comets, the aurora, terrestrial magnetism and its variations, nebulae and the zodiacal light. First, these facts are being established in connection with the pressure exerted by light which was pointed out by Maxwell and deduced by him from his electro-magnetic theory of light, which is, that when a pencil of light impinges perpendicularly on an opaque object, it produces a pressure on the surface of that object. This pressure is determined by the condition that if the object were set in motion with the velocity of light and the force against it kept up, the power to keep up the pressure would be equal to that carried by the ray of light.