124 



NATURE 



[April i8, 19 li 



pilot's loss of his sense of direction, and not in 

 any way to chang-ed stability of the machine. 

 Further, on p. 22 we find: "The main condition 

 that supplies stability to aircraft is 'lift,'" a 

 statement that surely needs no criticism ! The 

 author appears to possess a sense of humour, for 

 on p. 13, after cautioning the reader against the 

 erroneous expression "knots per hour," he states 

 that "a knot is equal to 6080 ft." The photo- 

 graphs illustrating the work are passable, but the 

 diagram on p. 83 is not. It purports to illustrate 

 the trajectory of a bomb dropped from an aero- 

 plane, but the tangent to the trajectory at the 

 moment the bomb leaves the machine is vertical 

 instead of horizontal ! Such errors as those in 

 the volume under review need stern criticism, as 

 they are liable entirely to mislead the unsuspect- 

 ing reader who takes up the subject for the first 

 time. Incidentally, there is scarcely a page of 

 the book free from g-rammatical error. 



(2) Mr. Dommett's " Dictionary of Aircraft " is 

 a very different type of work, and although some 

 of the definitions are somewhat weak, the gene- 

 rality are good and convey a concise idea of the 

 meaning of the terms defined. The book is likely 

 to be most useful to the non-technical reader, as 

 it is scarcely full enough to be regarded as a work 

 for technical reference. There are one or two 

 errors which need correction ; the density of air 

 is given as 0*807 lb- per cub. ft. instead of one- 

 tenth of that amount. Under the heading 

 "dynamic similarity" we are referred to "simi- 

 larity," but no discussion of the term appears 

 under this latter head. The definition of dynamic 

 stability might well be expanded, as this is a term 

 little understood by many readers of aeronautical 

 works. Despite these few minor faults, the work 

 should be of considerable utility, especially to the 

 casual reader who wants a brief definition of tech- 

 nical terms. The price seems a trifle high for a 

 paper-covered handbook of fifty-two pages, even 

 in war-time ! 



LIQUID FUELS. 



Liquid Fuels for Internal-comhustion Engines : 



. A Practical Treatise for Engineers and 



Chemists. By H. Moore. Pp. xv + 200. {Lor>- 



don : Crosby Lockwood and Son, 1918.) Price 



125. 6d. net. 



THE rapid development of the internal-com- 

 bustion engine has considerably changed our 

 methods of power production, and liquid fuels for 

 such engines being the most recent development, 

 it is not surprising that their scientific study is 

 still Incomplete in respect to this method of ap- 

 plication. The author considers it likely that the 

 employment of liquid fuels for steam raising will 

 entirely give place to their use in internal-com- 

 bustion engines. Referring to the use of engines 

 of the Diesel type for propelling ships, the author 

 says that this is at present prevented through in- 

 sufficient experience in building engines of very 

 large size and of building them of low weight in 

 proportion to the power they develop, but these 

 difficulties, he says, are by no means insurmount- 

 NO. 2529, VOL. lOl] 



able. Inexperience will be a vanishing factor, but 

 the weight is by no means a factor to be easlh 

 overcome, being dependent on the high initial 

 working pressures these engines require. . Few 

 engineers would care to predict the displacemeni 

 of the steam turbine by Diesel engines for the 

 high power demanded in modern battleships of 

 even moderate size. Indeed, on the American 

 coast there have been already cases where Diesel 

 engines have been displaced by steam. 



The liquid-fuel engine has, however, established 

 itself firmly for a number of purposes, and the 

 extension of the use of such engines has led to a 

 serious shortage of suitable fuels. As the author 

 points out, by suitable methods supplies can be 

 enormously augmented, but the future develop- 

 ment of these engines may be seriously retarded 

 unless steps are taken to provide additional 

 amounts. He instances the heavier grades of 

 petrol, so that a larger proportion of the crude oil 

 is available, the use of heavier fractions in vaporis- 

 ing engines, and the use of coal-tar products In 

 Diesel engines 



The book is divided into three parts, the last 

 section, which comprises nearly one-half, dealing- 

 entirely with methods of examination of liquid 

 fuels, embodying the author's experience in the 

 laboratory of one of the largest firms of Diesel- 

 engine manufacturers. This section will prove 

 of consWerable value to chemists engaged in fuel 

 work. 



The first part deals briefly with the raw 

 materials which furnish the different classes of 

 fuel — petroleum, coal tar, shale and lignite oils, 

 etc. Part 11. deals with the fuels classified under 

 the three types of engines in which they are ap- 

 plicable; those fitted with carburettors (petrol 

 motors), those fitted with simple vaporisers 

 (paraffin motors), and those of the Diesel and 

 semi-Diesel type, w'hich are fitted with fuel pumps 

 and atomising devices. Such a method of treat- 

 ment is open to objection, for many fuels are 

 applicable to engines of more than one type — 

 kerosene, for example, to each type. Necessarily 

 this method leads to considerable overlapping. 



Throughout the book generally there is evidence 

 of the author's practical familiarity with the 

 various fuels and the important characteristics to 

 be considered In their examination. The volume 

 will prove a serviceable guide to engineers and 

 chemists Interested in this rapidly developing phase 

 of the fuel problem. 



OUR BOOKSHELF. 

 Educational Reform. Speeches delivered by the 



Rt. Hon. H. A, L. Fisher. Pp. xvi+ioi. 



(Oxford : At the Clarendon Press, 1918.) Price 



IS. net. 

 The President of the Board of Education, who 

 has by common consent done so much to stir and 

 enlighten the public interest In the cause of educa- 

 tion by his numerous addresses in all parts of the 

 country, has wisely resolved to issue in this cheap 

 and accessible form a selection of his principal 

 speeches, two of which he delivered in the House 



