December rg, 1918J 



NATURE 



507 



There is evidently a certain amount of overlap- 

 ping in these movements. There has been formed 



within the last lew months in the North of 

 England an Association of Chemists with a similar 

 professed purpose, but this has been merged, at 



least so far as t lie principal leaders are concerned, 

 in the Institute ot Chemistry, the chartered bod) 

 to which nearl) all the well-qualified chemists in 

 the country are gravitating. Hut another step is 

 now being taken in the creation of a Federation of 

 Chemists which will include not only the highly 

 ■qualified, but also men of all grades, and this will 

 probable assume the features of a club with 

 libraries and meeting-rooms. Science is evidently 

 not going to be overlooked, but it would be un- 

 fortunate if any serious dissipation of energy 

 should ensue before such compromises can be 

 effected which will provide for the needs of all 

 branches ol science, pure and applied, and espe- 

 cially those eases in which, as between the 

 chemists, metallurgists, and engineers, mutual 

 help and recognition are most desirable. 



THE FUTURE DEVELOPMENT OF THE 

 INTERN. I /.-( OMB I STIO N ENGINE. 



A BRILLIANT piece of analytical work has 

 lately been given b\ Mr. H. R. Ricardo 

 to the North-easl Coast engineers and ship- 

 builders. 1 Mr. Ricardo takes as the title of his 

 paper " High-speed Internal-combustion Engines," 

 and in it he compares the modern high-speed 

 engine with the older slow-speed type, much to the 

 disadvantage of the latter not merely in relation 

 i" speed, but also in respect of the degree of skill 

 shown in design. There is great loree in 

 the arguments used, and the truth which is 

 evident in not a few of them may legitimately 

 be regarded as one of the outcomes of the war. 

 The war had the effect of drawing out and stimu- 

 lating the hitherto hidden abilities ol numbers ol 



getically minded and scientifically trained 

 engineers — mainly quite young men- -who in the 

 highly inelastic system ot pre-war days received 

 but trifling encouragement for either their inven- 

 tive or their organising powers. The State cared 

 little for scientific or technical research, and the 

 leaders of industry were in too many cases quite 

 as conservative as the State. Then came the 

 awakening. The perils and dangers of war re- 

 quired that, for the supreme cause of the safety 

 -of the State, this attitude should be completely 

 reversed- -and reversed it was. Wide scope was 

 at once given to all with inventive and scientific 

 ability 'in, result we ;e< in the amazing strides 

 made in aviation mainly the work of youth. 

 When, therefore, Mr. Ricardo compares the older 



- of internal-combustion engine with the aero- 

 engine ol to-day he is comparing not merelv two 

 engines, but also two systems, two worlds in fact 

 ..ne where the State is little concerned what tech- 

 nical developments its nationals may or may not 

 produce, and one in which the State, fighting for 

 its life, calls anxiously tot the help of all talent to 

 be found anywhere within its borders. 



nuuectioni of North-East Coast Institution of Engineers and Ship- 

 vol, xxxiv., October, ioi8. 



2564 VOL. 102] 



Bui lor the war aviation could not have devel- 

 oped at a pace in the least approaching that actu- 

 ally attained- and steadily maintained. This 

 development is, as regards both numbers and 

 efficiency, the outstanding technical achievement 

 of the past four years; naturally it has demanded 

 intensely rapid, even drastic, changes in the 

 [lower unit of such craft. The heavy loading put 

 on such engines has caused their design to be far 

 more difficult than that of other internal-combus- 

 tion engines; they may be required to run at high 

 power (and that involving unprecedcntedlv high 

 brake mean pressures) for so long as twenty hours 

 on end. Types which have been constructed to 

 weigh but two or three pounds per horse-power 

 and yet run for hours on full load will afford a 

 magnificent start to the aerial services of peace, 

 especially since the less strenuous specifications 

 of future operations will allow the engine to 

 operate normally at powers quite appreciably 

 below the maximum. The modern aero-engine is 

 close to the highest perfection possible for its 

 power and cycle. Any material further advance 

 must, it would seem, be by change of evele, 

 change of fuel, or perhaps a break away to some 

 new kind of prime mover altogether. 

 ' Mr. Ricardo correctly points out that "the 

 design of internal-combustion engines in this 

 country has during the last twenty years pro- 

 ceeded along two widely different lines directed 

 by separated schools. On one hand, we have 

 the designers of what may be termed the slow- 

 speed type of engine, who have consistentlv had 

 to compete with, and have based their designs 

 upon, steam-engine practice ; and, on the other, 

 we have the designers of small high-speed 

 engines who have appeared with the advent of 

 the motor-car. The latter have created a school 

 of thought of their own, and have developed along 

 lines which ate distinctly enterprising." The dif- 

 ference between high- and low-speed engines is by 

 no means confined to a matter of speed, since the 

 former usually run on petrol and the latter on gas. 

 This difference in fuel is very important, though 

 perhaps not permanent — a small "suction pro- 

 ducer " added to a "petrol engine " would enable 

 the latter to be run on gas directly derived from 

 coal fed into the producer. This may come, but 

 it seems to be some way off at present. 



The difference between the use of petrol and 

 gas is not merely one of supply and carriage, but is 

 also of a more essential nature. Petrol has certain 

 very valuable advantages. For one thing, a gas 

 mixture suffers a chemical contraction on com- 

 bustion, whereas a petrol mixture shows an ex- 

 pansion ; the evaporation of petrol in the carbu- 

 rettor lowers the temperature of the incoming 

 charge, so that the weight-volumetric efficiency of 

 the suction stroke is higher than with gas. The 

 disadvantages of petrol are less pronounced, 

 though they certainly exist; thus there is usually 

 some proportion of petrol which is not properly 

 1, and escapes combustion; and a stricter 

 limitation of richness of charge is necessary. 



These essential differences tend to complicate 

 any comparison of the usual high-speed with the 



