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"Screw Propellers," by Charles W. Dyson, U.S: N: 27 vols. text, 142:6° x 9 in. pages; Vol. IL, 32 Volume I 18 x 18 in. 2-page plates, 1913. John Wiley & Sons, New York. Price $7.50. For sale by Penton Publishing Co., 'Cleveland. This work in the main is a resume of papers by the author published in the Journal of the American Society of Naval Engineers during the past several years. It is a valuable con- tribution to the literature of a subject to which the very obscurity surround- ing actual working conditions and the impracticability of exact observation have lent, and continue to lend, un- flagging interest as evidenced by the standing of its investigators. Captain Dyson has had access to a mine of in- formation in the records of the Navy department and has been in _ close touch with its work during a period of very rapid development, and has had the further advantage of intimate as- sociation with that master-mind, David W. Taylor, in his experimental tank investigations. His conclusions are naturally, there- fore, based chiefly upon results ob- tained with naval vessels and from these are deduced the theory of design submitted. By far the larger propor- tion of propeller problems, however, arise in connection with ships not only of very different forms, but working under radically different conditions, and from those encountered in naval work and introduce factors which al- most never. confront the naval de- signer yet cannot be ignored. The author tacitly admits so much by casting aside the idea of designing from theoretical formulae as incorrect' and impractical and reducing avail- able methods to three; on results ob- tained with model propellers; and on actual trials of full sized propellers in service. He eliminates the first two as unsatisfactory and adopts the third and hence is restricted to the deduc- tions as above. Manifestly, therefore. conclusions based upon a type of ship with fine ends, deep and_ practically constant draft, allowing of the use of maximum diameters working in water of maximum density and employing relatively high speeds of revolution, are hardly trustworthy in the case, say, of a full modeled cargo ship, with a single screw working in a greatly disturbed wake and restricted in diam- eter because of a widely ranging draft and perhaps in shoal water. Never- theless, Capt. Dyson's work is a pains- taking effort towards the solution of what must probably always remain one of the most baffling problems in engineering. "Turbines Applied to Marine Pro- pulsion," by Stanley J. Reed. 174 pages, 7 x 10 in, D. Van Nostrand Co., New York, publishers. Price, $5. For sale by Penton Publishing Co., Cleveland, O. The contents of this volume, which comprise thirteen chapters, consist of a special course of lectures which were given by the author at the Naval Ar- chitecture Department of Glasgow university during the early part of 1912. The lectures, however, form only a basis for the volume, as obvi- ously they are greatly extended. The book is more especially intended for practical use and for this reason thermodynamic and mathematics are entered into as lightly as possible. The free use of entropy is made only on account of its forming a conveni- ent abscissae value for the charts. Nearly all the calculations have been made by means of a slide rule and graphics and are therefore correct only to the degree of accuracy that can be obtained by these methods. The progress made with turbines since their first application to practice has been very rapid and the author be- lieves that the pace will be equally fast in the future. After acknowledg- ing the untiring perseverance of Sir Charles A. Parsons, he attributes the striking development of the turbine for marine purposes to the progress- 'tude has been found at noon. ive policy of the British admiralty under the leadership of the late Sir William Henry White, who quickly perceived their advantages and as- sumed the responsibility of installing them. While it will be noted that no prefix is given to the title, the - book deals only with steam. turbines, as the present stage of the gas tur- bine is experimental. Detail design, which is largely a question of ordinary engineering, is not entered into. How- ever, the concluding chapter deals with astern turbines, cylinders, rotors, bearings, thrust blocks, steam pipes, and other details of design. " "Navigation by One Observation, by Capt. P. Thompson, 56 pages, 6 x 9 in. Longmans, Green & Co., New York; price, $1.20. For sale by Pen- ton Publishing Co., Cleveland, O. This book outlines the method of finding a ship's position at sea by one observation only and is intended for officers in the mercantile marine and for yachtsmen. Capt. Thompson is senior examiner of masters and mates at Trinity House, and is the author of "Navigation Simplified." Where one observation of a celestial body only is used for finding the longitude the re- sult cannot be verified until the lati- Where two observations have to be taken to find the ship's position, a delay of two or three hours must take place to al- low of a change of azimuth before the computation can be completed. These disadvantages are altogether avoided in the present work and the ship's position fixed by an altitude of either sun, moon, star and planet at any hour of the night and at almost every hour of the day when the atmosphere and weather are suitable for observa- tions. The author says that the com- putation can be made by an intelligent navigator in ten minutes. The num- erous examples which are worked out in the book are more graphic than any explanation. This little book should prove a very useful one to an experienced navigator.