November 25, 1920] 



NATURE 



423 



to determine the efficiency of various fuels and the 

 best conditions for the use of any fuel, and also to 

 compare the performance with the calculated figures 

 based on thermodynamic theory. 



Prof. VV. H. Watkinson described a dynamical 

 method for raising gases to a high temperature with- 

 out the use of high pressures, which consists in 

 drawing the gas into a cylinder through a partly 

 opened valve, so that the pressure in the cylinder is 

 only a quarter, say, of that outside, and then com- 

 pressing the gas up to the external pressure with 

 consequent rise in temperature. By a cascade 

 arrangement of several such pumps the temperature 

 could be raised sufficiently high to ignite the gas in 

 an internal-combustion engine. 



Dr. C. Batho read a paper on the partition of 

 the load in riveted joints, in which he explained that 

 he treated the riveted joint as a statically indeter- 

 minate structure, and applied the principle of least 

 work in order to determine the distribution of the 

 load between the rivets. The details of the method 

 have already been published in the Journal of the 

 Franklin Institute (U.S..^.) for November, 1916. The 

 author quoted some experimental results obtained 

 with an extensometer which supported his theoretical 

 treatment. 



Prof. J. T. MacGregor-Morris described and demon- 

 strated his portable direct-reading anemometer for 

 the measurement of ventilation in coal-mines. This 

 instrument, which is made by the Cambridge and 

 Paul Instrument Co., consists of an ebonite handle 

 carrying a cage containing four fine nickel wires, two 

 of which are exposed and two. shielded from the air. 

 These wires form the four arms of a Wheatstone 

 bridge, and the fjalvanometer is connected by mcnns 

 of a fk^xible wire passing through the ebonite handle. 

 The galvanometer is first used as a voltmeter to 

 adjust the applied voltage to the correct value for 

 the observed temperature of the air. It is then used 

 to indicate the out-of-balance bridge current, which 

 depends upon, and is used as an indicator of, thp 

 velocity of the air-stream. 



Messrs. H. T. Tizard and D. R. Pye read a paper 

 on specific heat and dissociation in internal-combustion 

 engines. .Mthough very little advance has been made 

 in recent years in the thermodynamical theory of 

 internal-combustion enpines, there have been great 

 practical advances, and the actual efficiency of a 

 modern high-speed engine is higher than the 

 theoretical efficiency calculated on the old specific heat 

 figures of Clerk and Lange. The temperature 

 reached is about 2500° C, but the specific heats 

 of the gases concerned were not known accu- 

 rately above 1500° C, and the extent to which 

 dissociation of CO3 and H,0 takes place was also 

 unknown. Data on these subjects are now avail- 

 able, having been obtained in Nernst's laboratory in 

 Berlin. The authors apply these data to the engine 

 and obtain results which are confirmed bv experiment 

 as regards variation of power and efficiency with 

 strentjth of mixture, with contpression ratio, and with 

 different types of fuel. Closelv allied with the fore- 

 fointj wan the paper by Sir J. B. Henderson and 

 Prof. Ha«s# with the attractive title "The Indicator 

 Diagram of a Gun." The diagram is not' obtained 

 experimentally, but hv calculating the pressure from 

 fhf trmperafure, which ran be determined only when 

 the specific heat and dissociation are known. The 

 temperature of the explosion is of the order of 

 3140° C. absolute, and It is calculated that of the 

 energy liberated from oa to 95 per cent. i.s converted 

 into kinetic energy in the projectile. A gun Is 

 a tvpe of internal-combustion engine, and very 



NO. 2665, VOL. I06'l 



similar difficulties arise in investigating the two 

 problems. 



.■\ very important but difficult subject is the action 

 in steam-nozzles, and a paper by Prof. A. L. Mellanby 

 and Mr. VV. Kerr recorded a great amount of careful 

 experimental work carried out at tlie Glasgow 

 Technical College, the data from which were analysed 

 and discussed in the paper. Pneumatic elevators for 

 the unloading of grain were invented in England, 

 but, as in many otiver things, it was in Germany 

 that later study and development took place. Prof. 

 Cramp, who had studied Continental practice before 

 the war and commenced a research on the factors 

 determining the efficiency of such apparatus, was 

 afterwards given a grant by the Department of 

 Scientific and Industrial Research to enable him to 

 continue the work. His paper gave an account of 

 the experiments made by him at Manchester Univer- 

 sity. To design apparatus intelligently one must be 

 able to calculate thie weight of grain which can be 

 lifted a given height through nozzles and pipes of a 

 given shape and size bv a given vacuum and a given 

 power. Whereas mechanical elevators can be made 

 to work with 75 per cent, efficiency, the pneumatic 

 type cannot reach a higher theoretical value than 

 40 per cent., and in practice falls far short of this. 

 In spite of this pneumatic elevators are used because 

 of their labour-saving qualities and freedom from 

 dust. 



The most striking and imaginative paper read 

 before the Section was that of Wing-Comdr. Cave- 

 Brown-Cave on airships for slow-speed heavy trans- 

 port and their application to civil engineering. The 

 author discussed the use of airships with ^ne or more 

 trailing air-barges for the transport of men and 

 material over virgin country through which a railwav 

 was being constructed or in which it was necessary 

 to carry on prospecting. In his opinion the present 

 stage of development of airships and of the methods 

 of handling them is such that their use for such 

 purposes is quite practicable and offers great 

 advantages. 



Prof. G. W. O. Howe discussed the efficiency of 

 aerials and the power required for long-distance radio- 

 telegraphy. Of the power supplied to an aerial, the 

 fraction which is radiated decreases with increase of 

 i wave-length, but, on the other hand, the longer waves 

 ; are transmitted around the earth with less attenuation 

 than shorter ones. On the latter point, however, there 

 are but scant empirical data ; on the usually accepted 

 assumptions the author calculated the power required 

 to produce a given strength of electric field at various 

 distances with different wave-lengths. Using the 

 optimum wave-length in each case, the power required 

 for a range of three or four thousand miles varies 

 as the sixth to the eighth power of the di,s. 

 tance. Prof. Howe mentioned that recent ex- 

 periments between .America and Italv indicated the 

 necessitv of much smaller powers than those 

 given in the paper. In conclusion, the author 

 {>ointcd out the need for extende<l research on this 

 subject to enable a network of stations to be designed 

 intelligently. 



In the concluding paper Dr. J. S. Owens gawe a 

 very interesting description of the removal bv drilling 

 and blasting of 11,000 tons of rock-reefs from the 

 bed of a river. No divers were employe<l, but holes 

 were drilled from n floating barge, using a ^-in. steam 

 drill. "Sausages" of dvnamite were fed into the 

 holes through a pipe and fired electrically in groups 

 of about eight hok's. The cost was a mere fraction 

 of what it would hnve been If divers had been 

 employed. 



