May i, 1913] 



NATURE 



In the present volume we have one-third of the 

 chapters attributed to each of the two authors, 

 and the remainder a joint production, whilst the 

 whole "correctly represents the opinions of both 

 writers." The subjects dealt with in the various 

 chapters include the development of the Otto and 

 Clerk cycles, ignition arrangements, speed regula- 

 tion, governing, gaseous fuels, petroleum and its 

 products, petrol engines, carburettors, heavy oil 

 engines, marine engines, and the future of internal 

 combustion motor-. There is also a somewhat 

 forbidding appendix on the acceleration of re- 

 ciprocating parts. 



Since its first publication in 1886 the book has 

 had for numerous reasons to be increased greatly. 

 It is only in comparatively recent years that the 

 petrol engine has become prominent ; now, of 

 course, it is without exception the most widespread 

 of all prime movers. In this volume Mr. Burls 

 deals chiefly with the petrol engine, and he has 

 certainly made it an interesting part of the book ; 

 he discusses ably and fully those problems on 

 which he is well known to hold decided views, 

 although his processes of argument are occa- 

 sionally obscure, especially when mathematical 

 treatment becomes necessary. The graphical con- 

 struction at the early part of chapter iv. for find- 

 ing the tangential effort at the crank-pin is un- 

 necessarily complicated, and is not likely to be 

 much used. 



A very interesting statement occurs on p. 433, 

 where Dr. Clerk describes his method of over- 

 coming the pre-ignition difficulty when working 

 wilh coke-oven gas or with other gases rich in 

 hydrogen. His plan is to replace some of the air 

 in the gaseous charge by cooled exhaust products ; 

 the effect is thus described : "The inert gas addi- 

 tion reduces inflammability by diminishing the 

 oxygen and by the diluting effect of the carbonic 

 acid and nitrogen, without reducing the total mass 

 of the charge." This is a most ingenious plan, 

 and it would be interesting to learn how much 

 of its beneficial effect is due to the lowering of the 

 compression temperature on account of the greater 

 specific heat of the carbonic acid, particularly at 

 the higher temperatures. 



The most useful recent work on the theory of 

 the internal combustion engine has been done by 

 the Gaseous Explosions Committee of the British 

 Association, of which until quite lately Dr. Clerk 

 was joint secretary. One of their discoveries was 

 the enormous proportion of the heat loss during 

 the expansion stroke which occurred at the crest 

 of the temperature wave. This was shown to be 

 a radiation loss and not a surface-cooling loss. 

 Nevertheless, we see on p. 517 that the rating of 

 petrol engines is discussed on the basis of the 

 NO. 2270, VOL. 91] 



heat loss being proportional to exposed surface 

 irrespective of temperature limits, and it would 

 have been better to have added to this assumption 

 some qualification. 



These are, however, minor points, and for the 

 book as a whole we have only praise. We have 

 no doubt it will be welcomed by British engineers, 

 who are accustomed to look on Dr. Clerk as the 

 chief authority on all that pertains to the gas 

 engine. His concluding remarks cannot fail to 

 hold not only engineers, but all who are interested 

 in the future of the internal combustion motor. 

 Dr. Clerk considers that although the problem of 

 improving efficiency is a fascinating one from the 

 scientific point of view, it is not at present of vital 

 importance, since present thermal efficiencies are 

 sufficiently good, and it is, he considers, much 

 more important to improve internal combustion 

 engines in other respects. He foresees much diffi- 

 culty in the way of making a gas turbine, and 

 suggests that progress is most likely to lie in 

 the development of the Humphrey idea, in which 

 water propelled by gaseous explosions is made 

 to do work in turbines. He thinks also that more 

 attention should be concentrated on the bitumin- 

 ous fuel producer as a means of gas production, 

 since for this country coal is and must long remain 

 the chief source of power. 



COMPARATIVE BIOLOGY. 



(1) Vorlesungen iiber vcrglcichende Tier- unci 

 Pflanacnkunde. By Prof. Adolf Wagner. 

 Pp. viii + 518. (Leipzig: Wilhelm Engelmann, 

 1912.) Price 11 marks. 



(2) Vergleichende PhysiolOgie wirbelloser Tiere. 

 By Prof. H. Jordan. Erster Band : Die Ernah- 

 rung. Pp. xxii + 73<S. (Jena: Gustav Fischer, 

 1913.) Price 24 marks. 



T 



Bernard's famous " Lecons sur les pheno- 

 menes de la vie communs aux animaux et aux 

 vegetaux " (1878), and we are aware that this is 

 saying a great deal. It has not the luminosity and 

 fascination of the French classic, but it is a sub- 

 stantial and original piece of work, to which we 

 would give the heartiest welcome. Many books 

 have compared the plant cell and the animal cell, 

 the plant metabolism and the animal metabolism, 

 and so on, but Prof. Wagner's aim is different. 

 It is to show how the plant-organism and the 

 animal-organism tackle the everyday problems of 

 life. Organisations built on different lines find 

 different, but in their way equally successful, solu- 

 tions of the same problems, and the comparative 

 study has been too much neglected. We have in 

 this book an admirable guide. 



