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274 ocean, leaden sky, and single moon," attempt a journey to Jupiter in the Callisto, a cylindrical car made with double sides of glucinum. It is protected against the intense cold of space by an interlining of mineral wool and charged with apergy, the opposite of gravitation. It is consequently repelled from the earth's surface until attracted by Mars and Jupiter, when the charge is tempered to prevent annihilation. The average speed of the ship is three hundred and eighty miles a second.

The celestial voyage is an interesting lesson in astronomy. The travelers enjoy a near view of our moon, go within ten miles of the satellites of Mars, pass through the nucleus of a comet, approach various asteroids, and finally, in a little short of twelve days, land upon Jupiter. The state of development there corresponds to the Carboniferous age upon earth. The explorers breakfast upon mammoth, while all about them are known and unknown monsters, turtles, tortoises, and jellyfish. The flowers through contraction of their fibers sing at sunset and attract the birds; but gigantic ants thirty feet long trouble the newcomers, and after a brief survey of Jupiter they depart for Saturn. There they meet spirits who materialize and tell them of many unknown laws of Nature, explaining the process of building a body from the elements. Through the services of one of these, Ayrault visits the earth in spirit form, and concludes that he would rather resume his terrestrial shape and return to our insignificant planet. Shortly after, the Callisto leaves Saturn and the adventurers are restored to earth.

The book is well illustrated, and perchance may prove to be a bypath to science.

book contains the substance of a course of lectures delivered before an audience of teachers of elementary chemistry in a summer school at Colorado Springs. Seven subjects are treated, namely: The birth of scientific chemistry, the phlogistic period, chemical classification, the atomic theory, kinds of compounds, molecular architecture, and chemical equilibrium. Obviously the volume is not a complete treatise on chemical theory or any division of it, and the author offers it as a "companion book" for students who wish "to recapitulate and coordinate the more important principles of chemistry before proceeding to more detailed and advanced works." The author has selected for attention those essential topics which are treated inadequately or not at all in current text-books, or which present especial difficulties to the student. He has aimed to show these topics in their proper perspective, and to point out the trend of modern research with respect to them.

a special dictionary is needed for any branch of science it certainly is for electricity. Electrical matters have a side of interest for the scientist, the business man, the mechanic, and for numerous users of electrical appliances. Moreover, the phenomena of electricity are so manifold and so peculiar, and the apparatus for exhibiting or utilizing them exists in such great variety, that a large vocabulary of electrical terms has necessarily arisen. This vocabulary, furthermore, is rapidly growing with the growth of electrical science, so that it can not be mastered without competent assistance. Such assistance Prof. Houston undertook to supply in 1889, when the first edition of this dictionary was issued. He and his publishers have spared no pains to keep up with the growth of the electrical vocabulary since that time, by issuing a second and a third enlarged edition. The present edition, which follows the second after an interval of scarcely two years, has been increased by twenty per cent, the additions being inserted as an appendix. Prof. Houston's dictionary deserves the term cyclopedic, for not only are the words and phrases carefully defined, but the nature or construction of the thing defined and the electrical principles applying to it are set forth, while a great many pieces of apparatus are figured, and many processes are illustrated by diagrams. There are five hundred and eighty-two illustrations in the volume, and over six thousand words, terms, and