July 8, 1922] 



NA TURE 



4i 



The Paris and Liege Meetings of the Institution of Mechanical Engineers. 



THE summer meeting of the Institution of Mechani- 

 cal Engineers was held on June 12-21 in Paris and 

 Liege. In Paris the meetings were held in the Hall 

 of the Societe des Ingenieurs Civils de France. At the 

 opening session M. Max Laubeuf, the president of the 

 French society, and the engineer who more than any 

 other has been responsible for the development of the 

 submarine, received the president, Dr. H. S. Hele-Shaw, 

 and members of the Institution of Mechanical Engineers, 

 and addressed a few words of welcome. M. Laubeuf 

 had expected to be away from France at the time of 

 the meeting, and the formal address of -welcome was 

 therefore delivered by the vice-president, Prof. Leon 

 Guillet. 



The first paper was by Prof. Edouard Sauvage, on 

 feed-water heaters for locomotives, in which various 

 types were described, and the economies that might 

 be expected from their use discussed. The second 

 paper was an important contribution from Sir Vincent 

 Raven on the electric locomotive. Broadly speaking, 

 there are three types of locomotives required for the 

 successful working of railways, namely : shunting, 

 freight or goods, and passenger locomotives. For 

 passenger traffic it is not so easy to standardise loco- 

 motives as for the other purposes, and considerable 

 difficulties are met with in designing high-speed loco- 

 motives of great power. Particulars of a number of 

 electric locomotives designed by the author and others 

 were given, but the most interesting was an experi- 

 mental locomotive that had been designed by Sir 

 Vincent Raven, and built by the North Eastern 

 Railway to haul a train of 450 tons, of sufficient power 

 to start from rest on a rising gradient of 1 in 78, to 

 reach a speed of 65 miles an hour on the level, and to 

 run with safety at 90 miles per hour. The paper is 

 an important one, and will arouse considerable interest. 

 The chief engineer of the Paris-Lyon Railway, who is 

 considering the same problems, spoke enthusiastically 

 of Sir Vincent Raven's work. The agreement of these 

 two engineers to compare their experiences is a real 

 example of that entente cordiale which such gatherings 

 must of necessity do so much to encourage. Lord 

 Montagu of Beaulieu, in a paper on mechanical vehicles 

 and road surfaces, directed attention to the economic 

 importance of good road surfaces. 



The first paper read on the second morning at Paris 

 was a very important contribution by Prof. A. Rateau 

 on the subject of rapid high-altitude flying. The 

 author pointed out that the aeroplane is the only 

 vehicle in which the resistance to travel is independent 

 of the speed, and is directly proportional to the weight 

 for the same angle of incidence. For high speeds, the 

 aeroplane must select a height at which the density of 

 the air is most suitable, and, providing the power of 

 the engine can be maintained, high speeds can most 

 easily be obtained at high altitudes. The rarefaction 

 of the atmosphere at high altitudes makes it impossible 

 without some special device to maintain the power 

 of the engine, and, furthermore, pilots and passengers 

 cannot exist in the rarefied atmosphere without special 

 provision of oxygen, or being in an air-tight chamber 

 to which air can be supplied under pressure. Prof. 

 Rateau has attempted to overcome the former difficulty 



NO. 2749, VOL. I io] 



by using exhaust gases from the engine to drive a 

 turbine compressor which will supply air to the engine 

 at ground-level pressure, and also, it is hoped, to the 

 pilot and passengers in the air-tight chamber. Although 

 in this country, in France, and in Germany a good deal 

 of attention has been paid to supercharging of the 

 engine in order to maintain power, Prof. Rateau's 

 paper is the most serious contribution that has been 

 published on the subject. In certain trials the turbo- 

 compressor was made to revolve at speeds up to 53,000 

 revolutions per minute, giving a peripheral speed of 

 670 m. per second at the tips of the compressor. In 

 the gas turbine, speeds were attained which gave 

 stresses due to centrifugal force equal to 123,000 times 

 the weight of the material. Moreover, the turbine is 

 worked at a temperature of from 650° to 750° C, and 

 thus very unusual demands are made upon the material. 

 Prof. Rateau's paper was followed by one on air- 

 compressors by Mr. W. Reavell, of Ipswich, and this 

 again by a paper on the supersaturated condition as 

 shown by nozzle flow, by Prof. A. L. Mellanby and Mr. 

 W. Kerr. It has been suggested that an explanation 

 of the discharge through a nozzle being greater than 

 that required by theory can be found by the assumption 

 that the rate of change of pressure in a nozzle is so 

 great that supersaturation of the steam takes place. 

 The assumption is apparently justified by Wilson's 

 experiments, but it is difficult to see how the conditions 

 for a Wilson effect could be obtained in a nozzle. 

 Prof. Mellanby's experiments confirm those of other 

 workers in showing that the flow is greater than could 

 possibly obtain if the steam did not become partially 

 supersaturated. In the apparatus used search tubes 

 were placed in the nozzles to determine the drop of 

 pressure along the nozzle, and from an examination 

 of these and the discharge through the nozzles, the 

 condition of the steam was obtained. The experiments 

 show that the flow at and near the dry state is excessive 

 when compared with the theoretical, but that the form 

 of the flow curve over a small range of superheat 

 beyond the initially dry condition is not in agreement 

 with the assumption of complete supersaturation. 



The last paper read at Paris was one by Prof. F. C. 

 Lea on the effect of temperature on some of the pro- 

 perties of metals, in which it was shown that the effect 

 of temperature on the elastic properties of metals may 

 be more important than upon the ultimate breaking 

 strengths. ' The significance of this paper was well 

 illustrated by the difficulties referred to by Prof. 

 Rateau in his paper on turbo-compressors. 



An interesting and important public lecture was 

 given by Prof. E. G. Coker, on Recent Photo-Elastic 

 Researches on Engineering Problems. The lecture was 

 illustrated by a number of large scale experiments, 

 showing the stress produced in wheel teeth transmitting 

 power and in material being cut in the lathe in 

 planing machines and in milling machines. The experi- 

 ments aroused much interest and enthusiasm, and the 

 lecturer is to be very sincerely congratulated upon the 

 success of a lecture necessitating the conveyance to 

 France of so much delicate apparatus. 



A distinguished gathering was held at the Hotel 

 Continental on Thursday, June 15. Prof. Leon 



