October 6, 1898] 



NATURE 



543 



question from another standpoint, if they will only read 

 a little wider into the context than the author allows them 

 to do in his work. We do not wish to impugn Dr. Tebb's 

 absolute honesty in this matter ; we are only astonished 

 that, with the materials at his disposal, much of which 

 he has evidently read very carefully, he has arrived at 

 the position indicated in this work. 



OUR BOOK SHELF. 



The Heat Efficiency of Steam Boilers : Land, Marine, 

 and Locomotive. With tests and experiments on 

 different types, heating value of fuels, analyses of gases, 

 evaporation, and suggestions for testing boilers. By 

 Bryan Donkin, M.Inst.C.E. Pp. xvi + 311. (London: 

 Charles Griffin and Co., Ltd., 1898.) 



The main value of this book will undoubtedly lie in the 

 tables, which fill about 100 of its pages, and give in an 

 admirably complete form the results of no less than 405 

 tests of the efficiency of steam boilers of almost every 

 type. The labour of collecting the material must have 

 been great, and the author has selected with judg- 

 ment the information needed, practically everything 

 wanted is to be found in the twenty-six columns of the 

 tables, and no useless matter has been incorporated. 

 The only addition which might have been made with 

 advantage is the temperature of the feed-water, especially 

 in those cases where no economiser was in use. Useful 

 summary tables are given on pp. 116, 117 and 118, and 

 in chapter xiii. the author discusses the general con- 

 clusions to be drawn from these trials, but without coming 

 to any definite decision. As pointed out in the book, the 

 wide variations in the efficiency of the same type of boiler 

 when worked under different conditions makes it impos- 

 sible to lay down any general laws, though the graphic 

 representation on p. 223 of the relationship between 

 efficiency and rates of evaporation per square foot of 

 heating surface per hour, is of much value, and should be 

 of use to the designer. 



In reference to the calculation of the heating value of 

 coal by Dulong's formula, there can be no doubt that it 

 gives results which are too small when compared with 

 calorimeter tests ; the figures will be found, however, to 

 agree much better when in the calculation no deduc- 

 tion is made from the hydrogen for the portion assumed, 

 apparently without reason, to be chemically united with 

 the oxygen. A valuable chapter is that dealing with 

 the transmission of heat through boiler plates, because 

 Blechynden's and Durston's recent experiments on this 

 important question are given in a very clear and concise 

 fashion for reference. 



The author hardly devotes enough space to the 

 description of the instruments for analysing furnace gases 

 and their use, and those unfamiliar with the appliances 

 and their working will find it difficult to teach themselves 

 much by merely reading these paragraphs ; they might 

 well have been amplified since, as the author points out, 

 the accurate analysis of the gases is the most important, 

 and certainly the most difficult, point in boiler testing. 



In addition to dealing with boiler testing, the author 

 describes many of the important accessories which have 

 been introduced of recent years to reduce the cost of 

 steam generation, such as mechanical stokers, patent 

 grates, economisers, superheaters, &c., and much inform- 

 ation as to the value of these devices will be found in the 

 chapters devoted to them. The author may be congratu- 

 lated, for his book is one which cannot fail to be a 

 standard reference work to all engaged either in boiler 

 construction or in steam generation. An admirable little 

 bibliography finishes up a series of useful appendices 

 which give full directions for carrying out boiler trials. 



H. B. 

 NO. I 5 10, VOL. 58] 



A Text-book of Geodetic Astronomy. By John F. 



Hayford, C.E. (New York : John Wiley and Sons. 



London : Chapman and Hall, Ltd., 1898.) 

 We must confess that the examination of this book has 

 proved a little disappointing. This disappointment was 

 probably inevitable from the circumstances in which the 

 book has been produced, and the object which it is in 

 tended to serve. It appears that in the Cornell Univer- 

 sity the students of civil engineering devote five hours a 

 week during one term to the study of astronomy. In 

 this short space of time it is found impossible to master 

 the contents of such a book as Chauvenet or other 

 recognised standard work, and to meet this difficulty this 

 book is put forward, not on the ground that it contains 

 as much information as a student should acquire, but as 

 much as he can acquire in the short time at his disposal. 

 The sacrifice of thoroughness and completeness to the 

 necessities of a particular University course can neither 

 meet with general approval nor result in the production 

 of a satisfactory treatise. 



The title scarcely describes the character or the pur- 

 pose of the book, which is mainly devoted to the practical 

 determination of stellar positions by means of portable 

 instruments. Considered from this point of view, and as 

 showing in detail the methods employed in the United 

 States Coast and Geodetic service, the book is not with- 

 out its interest. On its practical side, we can conceive 

 that it would be of use to those who have carefully read 

 the theoretical ; but to regard it as an efficient substitute 

 for Chauvenet, would be to make a great mistake in the 

 training of the student. The mathematical processes are, 

 the author tells us, purposely omitted ; but it would seem 

 that other things besides mathematics have been omitted, 

 which one would expect to meet in a work of this de- 

 scription. We should hope to find here a discussion of the 

 figure of the earth, and, as a practical matter of great im- 

 portance, a description of the method of measuring a base 

 line. These matters are passed over entirely, and other 

 important, but minute, results of observation get a very 

 bare mention. For instance, to the variation of latitude 

 only a page and a half is devoted. Pendulum experiments 

 and their results do not come within the scope of the book. 

 On the other hand, we get a fairly good account of the 

 sextant, the transit, the zenith telescope, of the determin- 

 ation of the errors of these instruments, and the method 

 of combination of observations. Some astronomical 

 tables are added which are likely to prove useful. 



Machine Drawing. Book 2. Part i. Machine Tools. 

 By Thomas Jones, M.I.Mech.E., and T. Gilbert 

 Jones, M.Sc. (Vic). (London and Manchester : John 

 Hey wood, 1898.) 

 Tins work is intended " for the use of engineering 

 students in science and technical schools and colleges." 

 It contains twenty-five lithographed plates, upon which 

 are represented the elevations and details of important 

 machine tools in actual use by expert engineers at the 

 present time. The plates include drawings of a drilling 

 machine, planing machine, stroke slotting machine, 

 stroke shaping machine, and forms of gearing. The 

 complete drawings of the three first-named machines 

 are coloured, and all of them are well executed. With 

 the explanatory text the engineering student will find 

 the work instructive and of real assistance. 



A Student of Nature. By R. Menzies Fergusson, M.A. 



Pp. 246. (London : Alexander Gardner, 1898.) 

 The late Rev. Donald Fergusson was many-sided in his 

 pursuits, and among his pleasures was the study of 

 natural history. One of the sections of the present 

 volume contains the papers written by him on rural life 

 and scenes, and they show that he was filled with " deep 

 feeling" by nature and its wild life, but neglected the 

 minute examination of natural olsjects essential to 

 scientific study. 



