Kindly keep your aueries on separate sheets of paper when corresponding about such matters as paten ts. subscriptions. books. etc. This preatlv facilitate answering your questions, as in many cases they have to be referred to experts. The full name and address should be given on every sheet. No attention will be paid to unsigned queries. Full hints to correspondents are printed from time to time and will be mailed on req uest. (12582) E. McGee asks: Would you be so kind as to give me an explanation of It statement made by Carhart and ' Chute in regard to the transformation of energy. They say: “The energy of the solar system is becoming all the time less and less available.” A. You omit one very important word in making your quotation from Carhart and Chute's Physics, page 77. That word is “therefore.” The sentence as given in the book is as follows: “The energy of the solar system is therefore all the time becoming less and less available.” Therefore refers back to what has preceded. The radiated energy of the sun and other kinetic energy, which is employed in doing work in nature or for man's needs, is wse/ttZ energy. Ail else is useless, and becomes waste heat. So the authors say therefore the amount of energy which is available for useful purposes is all the time becoming less and less. It seems to be a plain statement. The sun is radiating heat all the time into space, and this heat does not, so far as we can determine, do any useful work. It reduces the available energy of the sun and is lost to us. There is less that we can have, less that is available. (12583) R. J. M. asks: Why does silver or silverware. when placed in an aluminium vessel with boiling water, come out with a brilliant appearance as if new? Please give me the reason. A. The cleansing of silver as you describe is an electrical process. A feeble electric current is produced between the silver and the metal pan, and a new and fresh surface of the silver is exposed. (12584) H. E. says: An argument arose regarding the following questions, and I would be pleased if you would give me some information regarding same. Wbat is the horse-power of an engine 10 X 10 at 100 pounds pressure? If a suitable size low pressure be added to a 10 X 10 engine at 100 pounds pressure, what horse-power would it develop? A. Your question involves a large part of the theory of steam engineering. The horse-power of the engine depends upon the speed of the engine (which you do not give) as well as upon the cut-off and consequent expansion and mean effective pressure, which latter is always less than the initial or boiler pressure. If a 10 X 10 engine is operated at one-quarter cut-off and 100 pounds steam pressure by gage, the mean effective pressure (disregarding all losses) is 68'A1 po unds above vacuum, and the pressure at the end of the stroke will be 29 pounds above vacuum. If the steam is exhausted at the above 29 pounds pressure, the horse-power of the engine will be about 15 If, however, this steam is now turned into a low-pressure cylinder 20 inches diameter and 10-inch stroke, an approximate horse-power of 15'A1 can be developed by expanding the steam to a low terminal pressure and exhausting into a condenser. The engine has now become a compound. But the same power could be developed (theoretically) by operating the low-pressure cylinder alone at 1/16 cut-off, and omitting the high-pressure cylinder. The only advantage in using the two cylinders, that is, a compound engine, is in the improved economy due to expanding the hottest steam in a cylinder which is hotter, on the average, than the temperature of the second cylinder, in which cooler steam is worked. If an engine could be made with a single cylinder of some imaginary material without any conductivity or capacity for heating, it would do all that a compound engine could do. If a glass cylinder were possible to operate, there would be no advantage in point of economy in compound engines, as a single large cylinder of glass would do all the work of a series of two, three, or more of a heat-absorbing metal like iron, brass, and the like. (12585) A. B. F. says: I would be pleased to know if the combination of gasoline and coal oil (as used in lamps) in a gasoline engine, will produce more power than gasoline alone. Please give B. T. U. of gasoline, also of naphtha and coal oil. A. Gasoline and kerosene have different specific gravities, and if mixed for use in an engine, gasoline will evaporate first and leave the heavier part of the coal oil for the last. The kerosene has a greater fuel value than gasoline per gallon, though very closely the same per pound. Kerosene is a cbeaper fuel than gasoline, both because of its slightly greater heat 'value and because of its much lower cost per gallon. The fuel values of tbe various petro--leum products, such as gasoline, benzine, kerosene, etc., are over 20,000 B. T. U. per pound, and differ little, one from the other. The beginning of Robert Grant's The Convictions of a ' Grandfather Introducing the Fred and Josephine of “The Reflections of a Married Man” and “The Opinions of a Philosopher,” their children, and their children's children. The author deals with modern life, its problems and interests, in a delightfully shrewd and humorous way, touching upon all its latest questions. Two Half-Told Tales: An old game in the odor of. sanctity, by Henry van Dyke. abbey's last mural paintings, by Royal Cortissoz. Illustrated with the artist's additional mural decorations for the Capitol at Harrisburg, and with studies of individual figures. the sheep of the desert, by Kermit Roosevelt. An account of a hunting trip in the Mexican Desert. Illustrated with the author's photographs. YOU WILL WANT TO READ IN 1912: "The Turnstile,” A. E. W. Mason's serial.Senator Lodge's Reminiscences. John Fox, Jr.'s novel, "The Heart of the Hills."President Finley's “Traces and Influence of France in the Settlement of America.” The romantic story of the changes that have followed the old French explorers — La Salle, Marquette, Joliet, and others. Price Collier's "Germany and the Germans." "The Witching Hill Stories,” by E. W. Hornung, creator of Raffles. Send (or a Prospectus, and at the same time send your subscription. $3.00 a year; 25c. a number CHARLES SCRIBNER'S SONS. NEW YORK The Scientific American Cyclopedia of Formulas The Most Complete and Authoritative Book - of Receipts Published eries" r of the Scientific American Partly Based on the Twenty-Eighth Edition of • The Scientific American Cyclopedia of Receipts, Notes and Queries “ Edited by ALBERT A. HOPKINS, cw Edit THIS is practically a new boot book and has called for the work of a corps of specialists for more than two years. Over 15,000 of the most useful formulas i-| and processes, carefully selected from a collection of .....j nearly 150,000, are contained in this most valuable volume, nearly every branch of the useful arts being represented. Never before has such a large collection of really valuable formulas, useful to everyone, been offered to the public. The formulas are classified and arranged into chapters containing related subjects, while a complete index, made by professional librarians, renders it easy to find any formula desired. "As Indispensable as a Dictionary and More Useful" Following /a a List 0/ the Chapters; I. 11. iii. iv. v. vi. vII. viii. DC X. XI. XII. XIII. XIV. Accidents and Emergencies. Agriculture. Alloys and Amalgams. Art and Artists' Materials. Beverages; Non-Alcoholic and Alcoholic. Cleansing, Bleaching, Renovating and Protecting. Cements, Glues, Pastes and Mucilages. Coloring of Metals, Bronzing, etc. Dyeing. Electrometallurgy and Coating of Metals. Glass. Heat Treatment of Metals. Household Formulas. Ice Cream and Confectionery. XV. Insecticides, Extermination of Vermin XVL Lapidary. Art, Bone, Ivory, etc. XVII. Leather. XVIII. Lubricants. XIX. Paints, Varnishes, etc. XX. Photography. XXI. Preserving, Canning, Pickling, etc. XXII. Rubber, Gutta-Percha and Celluloid XXIII. Soaps and Candles. XXIV. Soldering. XXV. Toilet Preparations, including Per. fumery. XXVI. Waterproofing and Fireproofing. XXVII. Writing Material, Appendix: Miscellaneous Formulas; Chemical Manipulation; Weights and Measures; Index. SEND FOR DETAILED ILLUSTRATED PROSPECTUS Octavo (6^ x 8 %: inches), 1,077 Pages, 200 Illustrations Price, in Cloth, $5.00, Net. HalfMorocco, $6.50, Net, Postpaid MUNN&CO., Inc. Publishers, 361 Broadway, New York City