NA TURE 



45: 



THURSDAY, SEPTEMBER 7, 1905. 



MARINE ENGINEERING. 



Marine Engines and Boilers, their Design and Con- 

 struction. Based on the work by Dr. G. Bauer. 

 Translated from the second German edition by 

 E. M. and S. Bryan Donlvin. Edited by Leslie S. 

 Robertson. Pp. xxviii + 744. (London: Crosby 

 Lockwood and Son.) Price 255. net. 



THIS considerable work fills a gap in English 

 engineering literature. For while the related 

 subject of naval architecture has been treated by 

 writers of authority, there is no very good modern 

 book on marine engineering. Dr. Bauer states that 

 it is intended to be a condensed treatise, embodying 

 the theoretical and practical rules used in designing 

 marine engines and boilers. But though thus limited 

 in scope, it treats only of the most modern types and 

 excludes even modern engines and boilers of special 

 tvpes. .As might be expected from the engineer-in- 

 chief of the Vulcan Works at Stettin, the machinery 

 of warships and of some of the great German Atlantic 

 liners are very fully illustrated. There is not a great 

 deal of theoretical investigation, but what there is 

 bears very definitely on design, and is sound so far as 

 it goes. Perhaps the most valuable part of the book 

 is the great amount of tabulated information about 

 the proportions of the machinery in good examples 

 of modern practice. There is also a very large collec- 

 tion of those empirical or semi-empirical rules, based 

 on extensive practical experience, on which engineers 

 necessarily so much rely. There is reason to be grate- 

 ful that an engineer so distinguished as Dr. Bauer, 

 with the care of a great factory on his shoulders, 

 should have found time to produce such a systematic 

 treatise, and that he has been able to obtain the 

 aid of some of his principal technical assistants in 

 dealing with parts of the subject. 



The book has been excellently and competently 

 translated, and the translators have undertaken the 

 necessary, but very laborious, task of converting the 

 numerical statements of formulae from the metric to 

 English measures. However bad our English sys- 

 tem of measures may be, English engineers can only 

 think and work in English measures, and the trans- 

 lation would have lost very much of its usefulness if 

 the conversion had not been made. Mr. Leslie S. 

 Robertson, who has edited the volume, has had prac- 

 tical experience in this branch of engineering, and has 

 already published valuable works relating to it. His 

 name is a guarantee that the adaptation of the work 

 for English readers has been, from the technical point 

 of view, thoroughly well done. 



The general arrangement of the book is convenient. 

 Part i., which occupies four-tenths of the volume, 

 deals with the main engines. First, indicator 

 diagrams are discussed, and the application of theo- 

 retical diagrams in settling cylinder proportions. The 

 well known method of constructing theoretical 

 diagrams from a diagram of the volumes occupied by 

 NO. 1871, VOL. 72] 



the steam is given, and an example worked out. The 

 remark is made that " the diagrams so obtained show 

 the characteristics of actual diagrams, but their mean 

 pressures are naturally much higher than they would 

 be in actual practice." That is not our experience. 

 If the data are rightly used, there is a fairly close 

 approximation between the theoretical and actual 

 mean pressures. It is a case in which the precise law 

 of expansion assumed does not very much affect the 

 result. There is one other small point in this chapter. 

 The ratio of an actual to a theoretical diagram is 

 called an " efficiency " (p. 17). Tliis leads to the 

 awkward statement on p. 35 that " the efficiency of 

 triple expansion engines is less than that of single 

 cylinder engines." If the more usual term " diagram 

 factor " had been used instead of efficiency the state- 

 ment would be less misleading. 



Next there is a very short section dealing with some 

 thermal circumstances affecting the utilisation of 

 steam. This is too brief to be satisfactory, even from 

 the point of view of engine design. For mstance, the 

 loss due to cylinder condensation is explained by say- 

 ing that " heat is vi^ithdrawn from the steam at high 

 pressure and restored to it at a lower pressure " 

 (p. 37). The essential point that the heat is chiefly 

 restored during exhaust is not mentioned. So the 

 economy of multiple expansion engines is traced to 

 reduction of temperature range. But the re-evapora- 

 tion during exhaust from one cylinder increases the 

 work in the next. In other respects also the ex- 

 planation is deficient. However, the thermodynamics 

 of steam engines is fully given in other treatises. An 

 important section follows, in which the stroke, speed, 

 and turning moment are discussed. The theory of 

 torsional vibrations is given, and practical 

 methods of determining the critical speed at 

 which liability to strong torsional vibrations occurs. 

 In connection with this there is a brief but clear and 

 practical treatment of the problem of balancing. Then 

 the arrangement of main engines is explained, and 

 there is a long section dealing with the proportions of 

 engine details and including a sufficient account of 

 valve diagrams. 



Part ii. deals with pumps. Part iii. discusses shaft- 

 ing, and in connection with this ship resistance, and 

 the proportioning of propellers. German writers are 

 adepts at tabulating coefficients and data, and the 

 tables in this section are excellent. Part iv. is on 

 pipes and connections. Part v. deals with steam 

 boilers, and is chiefly descriptive of modern types. 

 Here again the tabulated data from actual cases is 

 information of the most useful kind, and the rules of 

 the classification societies, which leave the engineer 

 very little discretion, are fully given. The last sec- 

 tion gives some account, rather too much condensed, 

 of instruments used in steam engine and boiler trials. 

 To many readers an account of Fottinger's torsion 

 indicator for measuring the effective horse-power of 

 engines by observing the torsion of the screw shaft 

 will be interesting. Hirn first used a torsion dyna- 

 mometer of this kind. As a diagram of the torsion 

 angle is obtained, the variation of the power trans- 

 mitted can be determined. 



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