Principles of Physics. By William Francis Magie, Ph.D., Henry Professor of Physics in Princeton University. New York: Tke Century Company, 1911. 570 pp. The author's name is sufficient guarantee for the general excellence of the book before us. It is very remarkable how much information has been condensed into a volume so small, considering. the boundless scope of the subject. Moreover, the information is thoroughly up-to-date. In turning over the pages we have found the Brownian movement and Per-rin's recent work duly considered in their relation to the kinetic theory. Similarly the chapter on “Electricity and Matter” presents in simple but clear terms some of the fundamental facts upon which the modern views on the subject are based. A brief note is also devoted to the phenomenon of radioactivity. There is little criticism to offer. The opening paragraph of the first chapter attempts a definition or description of “physics,” and can hardly be said to be quite successful. There are some things that can not be rigorously defined, and probably the scope of physics is such. One is almost tempted to say that “physics” is all science which has not been for one reason or another (not necessarily a very good reason) been given some other name —and even that may be physics. One can not help regretting that it should be necessary or desirable in a book of this kind to avoid the use of the calculus, often at the cost of much complication. So much can be done in elementary physics with a small stock in trade of the methods of the calculus, that it would seem well worth the while to arrange the student's courses in mathematics in such manner as to avoid the necessity of working out from first principles every case of “proceeding to a limit.” In the development of tile absolute temperature scale, the ideal gas is introduced as a “guide” for the choice of the temperature function which shall enter into the expression for the efficiency of a heat engine. It appears preferable to develop this function without reference to any specific properties of the working substance. Making use of an “ideal gas” (which does not exist) gives an appearance of unreality to the argument, and is apt to leave in the mind of the young student an impression that the argument in some way depends on the properties of the “ideal gas,” whereas what one is particularly anxious to impress upon the learner is the fact that the efficiency is wholly independent of the properties of the working substance. The general scope and arrangement of the book may be gathered from the main headings, which are as follows: Book 1— Mechanics. 1. General Notions About Forces. 2. Statics. 3. Dynamics. 4. Mechanics of Liquids. Book II—General Properties of Matter. 5. Gravitation or Mass Attraction. 6. Elasticity. 7. Capillarity. 8. Gases. 9. Friction. 10. Diffusion. Book Ill—.Sound. 11. Sound and Sound Waves. 12. Sounding Bodies. Book IV—Heat. 13. Temperature and Heat. 14. Thermal Relations of Bodies. 15. Heat and Energy. Book V—Light. 16. Geometrical Optics. 17. Physical Optics. Book VI—Magnetism and Electricity. 18. Magnetism. 19. Static Electricity. 20. The Electric | Current. 21. Electricity and the Ether. 22. Electricity and Matter. Bungalows. Their Design, Construction, and Furnishing. With Suggestions also for Camps, Summer Homes, and Cottages of Similar Character. By Henry H. Saylor. Philadelphia: The John C. Winston Company. 4to.; 188 pp.; illustrated. Price, $1.50 net. Bungalows, springing .up mushroom fashion all over the land, have imparted a not unpleas-ing variety to our countryside architecture. Mr. Saylor's papers are aptly introduced by Burgess Johnson's “Bungal-Ode.” The advantages and limitations of the true bungalow are impartially set forth, and under the heading “Types” we are given, in beautiful plates and succinct description, more than a score of houses scattered from the Atlantic to the Pacific coast. Bungalows for seacoast, woods, and hills are given separate consideration, and chapters on “Plan,” “Foundations,” “Walls,” “Roofing,” and “Interior Finish” tell what the prospective builder needs to know. Even the fireplace, furnishings, lighting system, water supply and sewage disposal are treated at some length, and the setting of flowers, vines and shrubs, an important matter from an artistic point of view, Is the subject of a final chapter. The large pages, fine paper. clear plates and good printing make the book a desirable one to own, and the common-sense manner in which the author presents his knowledge and advice places the seal of practical value upon what would still be a work of beauty and suggestive inspiration even without so Informing a text. Practical Silo Construction. By A. A. Houghton. New York: The Norman W. Henley Publishing Company, 1911. 69 pp.; 20 illustrations. Price, 50 cents. We have before taken the opportunity to mention favorably the earlier Issues of these “Concrete Worker's Reference Books.” The treatise in hand, No. 3 of the series. comprises directions for constructing concrete silos of various types. Full data and working drawings are given, and unpatented forms and molds are shown for the building of monolithic and block silos. Do It Now — ForYour Family HUT” Subscribe to-day, sending $1.75 for 1912, and get all the issues -__§ of The Companion for the remaining weeks of 1911 Free. On Jan. I, 1912, the price will be advanced to $2. See offerbelow. THE YOUTHS COMPANION Do you realize that the contents of The Youth's Companion for a year, published in book form, would make 30 volumes of the best and most varied reading? The 52 issues for 1912, for instance, will be equal to 1 Serial Stories, the kind you V UIS wish never would end, each selling for $1.50 in book form. 2TT 1 Articles by Famous Men and V UIS Women. Travel, Science, Invention, Biography. 3IT I Current Events, The Doctor's V UIS Weekly Counsel, Science, Wit and Humor, Editorials, etc. I Sketches, Anecdotes, Selec-VU1S tions, Social Topics, One- 1 For Boys on Expert Training V OIS for Athletic Sports—Football, Sprinting, Swimming, etc. 8IT 1 Each containing some thirty V UIS complete stories—Adventure, Heroism, Humor. 2\Z_1_ For Girls and the Household, VU1S Ideas in Dress, The Family Table, Profitable Occupations. 3 _1_ Jingles and Stories for the O V OIS Little Folks, Puzzles, Beauti-Minute Stories. ful Pictures. ALL FOR $1.75 — AND EVERY LINE WORTH WHILE. Fall Prospectus for /9/2 sent Free to any address with Sample Copies of the Paper. ALL THE REMAINING 1911 ISSUES FREE. If you subscribe at once, cutting out and sending this slip (or mentioning this publication) with $1.75 for the fifty-two issues of the Volume for 1912. you will receive 1. All the Issues for the Fifty-Two Weeks of 1912. 2. All the Issues for the Remaining Weeks of 1911, including the Holiday Numbers. 3. The Companion's Art Calendar for 1912, Lithographed in Ten Colors and Gold. Your last chance to get The Youth's Companion at the present price. On Jan. 1. 1912. the subscription will be advanced to $2.00. Subscribe to-day and save 25c. - ; Apia? THE YOUTH'S COMPANION, BOSTON, MASSACHUSETTS. Every Man Who Owns A Razor Every woman who owns a knife—Every man, woman or boy who owns an edged tool—will never realize what smooth, keen cutting sharpness is until demonstrate il— \__ Carborundum is the most remarkable sharpening agent the world has ever known. Hard and sharp and fast cutting as a diamond—smooth and velvety as the finest natural stone. Made into hones and sharpening stones of every size, shape and grade— for every possible sharpening need. 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