Supplement to ""Nature," March 13, 1902. 



to judge whether the cylinder-cooling devices, wearing 

 surfaces, and other matters which ought to be propor- 

 tionate to the power developed, were in these cases 

 sufficient for their purpose. He further points out 

 that none of the tests given by him give any fair com- 

 parison as to the relative power obtainable from motors 

 using light petrol of the specific gravity of 068 as com- 

 pared with the heavy oils having a specific gravity of 

 o'SS. Apart from the increased difficulty of vaporising 

 the heavy oil, the efficiency obtained ought to be propor- 

 tionate to the weight, and when these oils are used as 

 heating agents, tested by the amount of water evaporated 

 for a given weight of fuel, it is found in practice that 

 this is so, and that the evaporative efficiency does vary with 

 the weight. 



His chapter on carburettors or vaporisers is somewhat 

 disappointing. After all, the use of the carburettors is one 

 of the main features which distinguish the modern petrol 

 or heavy oil motor from the gas engine. After describing 

 the two classes of carburettors for light oil, i.e. the surface 

 vaporiser and the spray-making vaporiser, he describes a 

 number of varieties of these two forms, without, however, 

 giving any information as to their comparative efficiency 

 or successful use. His conclusions as to the difficulties in 

 using vaporisers heated by the exhaust gases or other- 

 wise which are necessary when heavy oils are used are 

 interesting and in the main correct. This part of the 

 subject is of the greatest interest and importance, as an 

 enormous development in the use of internal combustion 

 engines for heavy vehicles would follow on a satis- 

 factory solution of the problem of vaporising the heavy 

 oils. Although for many years past the heavy oil 

 stationary engine has taken its place as a well-known 

 trustworthy commercial article, the use of heavy oil in 

 the same internal combustion engine in motor cars 

 has turned out to be a problem offering so many 

 difficulties that up to the present hardly any maker of 

 internal combustion engines has dealt with heavy oil 

 with any reasonable degree of success. 



One of the best-written chapters in Mr. Beaumont's 

 book is that on electric ignition. This somewhat diffi- 

 cult matter is dealt with very exhaustively and so clearly 

 that a reader need not be an electrical engineer to under- 

 stand it. The various sources of electric energy which 

 are used to give the spark and the sparking plugs and 

 accessories necessary are, as a whole, correctly and 

 clearly set out. I can hardly think, however, that 

 Figs. 277 and 280, giving the diagram of magnetic 

 field of the Bosch inductor generator, are correct. At 

 the same time, they are scarcely necessary far making 

 clear the author's meaning. 



The author here gives at considerable length, not only 

 the main features, but most of the details of construction 

 of the vehicles used by the London Electric Cab Co. 

 which had already proved a failure at the time that he 

 wrote his description. .Since that time great advances 

 have been made in the construction of electrically driven 

 vehicles, chiefly in the improvement of the accumulators 

 themselves, so that we believe it has now been ascer- 

 tained that electrically driven vehicles can now be put on 

 the streets and worked at a very reasonable cost for 

 maintenance ; in fact, already the cost. for maintenance 

 of the accumulators is less than that of the rubber tyres. 

 NO. 1689, VOL. 65] 



Jenatzy's electrical vehicle, " La Jamais Contente," 

 which attained a speed of 65'8 miles an hour, is described 

 as having accomplished the greatest speed ever reached 

 on a high road, but since that time much higher speeds 

 have been recorded by the Mors and other petrol-driven 

 vehicles during the time of the Paris-Bordeaux and other 

 great French races. 



Some space is devoted to the consideration of modern 

 steam vehicles as made by Serpollet and by various 

 American firms, such as Stanley and Whitney. It is 

 to be regretted, however, that the descriptions of the 

 flash boiler used by Serpollet are so very meagre, for un- 

 doubtedly this steam generator needs very careful study, 

 as it bids fair to bring steam once more into use as a 

 propelling power for light vehicles. Vehicles of the 

 Stanley, or "locomobile" class as they are now called, 

 are so common in the streets of London that everyone 

 has noticed their satisfactory and quiet running. Mr. 

 Beaumont's description of the "Stanley" vehicle is very 

 complete. 



A chapter is devoted to the description of the heavier 

 motor vehicles used for transport of goods, and of which 

 we have heard so much in connection with the Liverpool 

 trials and morerecentlyduring theWarOfficemotor-wagon 

 trials at .Aldershot. Several of these vehicles are de- 

 scribed with considerable minuteness, but the author 

 omits to tell us why it is that up to the present internal 

 combustion engines have not come into use at all largely 

 for these vehicles. Quite at the end of the book we find 

 one or two chapters dealing with matters which are com- 

 mon to all classes of mechanically propelled vehicles, 

 such as questions of vibration, balancing motors and 

 pivoted steering axles. The latter chapter contains 

 several errors, the chief of which are due to careless 

 editing. For instance, in discussing the question of the 

 side rub of wheels on the road on p. 570, we find dis- 

 tance H described as a number of degrees, and the 

 proper angle of the outer wheel is called " a tangent to a 

 curve." Again, in a description of the Peugeot float feed 

 carburettor on p. 162, cock H is said to be for emptying 

 the carburettor, whereas it is well known that it is not 

 used for this purpose, but fulfils the rather important 

 function of admitting any required quantity of air to the 

 carburettor. 



Apart from these errors, and several others of the same 

 kind which are certain to be found in a work containing 

 so much matter, the whole of the descriptive part and 

 illustrations may be generally described as excellent. 

 The same cannot be said of chapters iv., v. and vi., 

 which deal with the general questions of road resistance, 

 resistance due to gravity, and power required, air and 

 wind resistance. In these the author has got together 

 a number of tables recording the results of several 

 experimenters on road resistances, which are confusing 

 and contradictory, as he makes no attempt to explain 

 them or reconcile them in any way. 



The subjects of air and wind resistances, which are of 

 some importance, are summarily dismissed in one page of 

 thirty-six lines containing a formula, i.e. that connecting 

 air pressure and velocity, which is most certainly in- 

 correct. Here, however, the author can hardly be blamed, 

 as this question of wind pressure and air resistance is one 

 of great difficulty. Most of those who have experimented 



