October 13, 1904] 



NA rURE 



585 



ESGINEERIXG AT THE BRITISH 

 ASSOCIATION. 

 A T the conclusion of the president's address an interest- 

 ■^ ing function took place. Dr. Schroter, on behalf of 

 the German Society of Civil Engineers, presented to Mr. 

 Parsons the society's gold medal. Dr. Schroter, in making 

 the presentation, directed attention to the conspicuous part 

 which had been played by the president in the advancement 

 of science and its application to practical purposes, and he 

 mentioned that the society which he represented consisted 

 of no less than 19,000 members, and they were proud to 

 think that they were the first engineering society to 

 recognise by a public award the man to whose genius the 

 success of the steam turbine was due. 



The afternoon of this day of the meeting, Thursday, 

 August 18, was devoted to a lecture by Mrs. Ayrton on 

 the origin of sand ripples. The lecture drew a very 

 large audience, and was illustrated by lantern slides, 

 diagrams, and by a number of most interesting e.xperiments. 

 The e.xperiments were carried out by means of tanks with 

 g^lass sides, which were caused to reciprocate, and waves 

 were thus set up ; the actual formation of ripples could, 

 therefore, be seen going on. Mrs. .\yrton was of opinion, 

 and showed this fact bv some of her experiments, that when 

 water was Rowing quite steadily in one direction, that is, 

 without oscillation or wave fnotion. and without any dis- 

 turbance, sand ripples could not be produced, and that such 

 a flow of water over previously e.xisting sand ripples would 

 tend to obliterate them. It may be mentioned that on this 

 point she disagrees with Prof. George Darwin, who gave 

 one of the evening lectures, and dealt with the same subject. 



The first three papers taken on the morning of Friday, 

 August 19, were concerned with internal combustion motors, 

 viz. flame temperature in internal combustion motors, by 

 .Mr. E. Dugald Clerk ; the specific heat of gases at high 

 temperature, by Prof. H. B. Di.xon ; and the calorimetry 

 of exhaust gases, by Prof. B. Hopkinson. Mr. Clerk, in 

 the introductory portion of his paper, stated that had we 

 lived in a world of a much denser atmosphere, there was 

 every probability that the internal combustion engine would 

 have developed on somewhat different lines, that is to say, 

 that the non-compression engine would have been much 

 more successful. The author then described a method he 

 had introduced by which it was possible to reduce the 

 maximum temperature reached in the engine at the time of 

 explosion and still maintain throughout the working stroke 

 a high average pressure, the principle upon which he worked 

 being to produce, as it were, an artificially increased atmo- 

 spheric pressure. An additional charge of air, compressed 

 by a pump, passed into the cylinder after the working charge 

 had been completely drawn in, and Mr. Clerk showed that 

 in one set of experiments he was able to increase the 

 thermal efficiency from 287 per cent, to 344 per cent., re- 

 ducing at the same time the maximum temperature from 

 1700° C. to 1200° C. The National Gas Engine Co. had 

 constructed to his designs an engine of 300 h.p. to use pro- 

 ducer gas, in which this system of air supercompression was 

 used ; the front end of the cylinder was arranged to act as 

 the pump for compressing this additional air supply, and 

 the pressure of the charge was raised by this means about 

 7 lb. per sq. inch above the atmospheric pressure. Mr. 

 Clerk also utilised some of this compressed air for 

 scavenging purposes. 



Prof. Di.xon in his paper dealt with the experiments he 

 has been carrying out for many years on the specific heat 

 of gases at high temperatures. He stated he had proved 

 that it was impossible completely to burn carbonic oxide 

 gas at very high temperatures. He had found as a general 

 result of his experiments that in the case of carbonic oxide 

 the specific heat rose with the increase of temperature up 

 to a certain point, and then dissociation began. Prof. 

 Dixon then described by means of blackboard diagrams 

 some exceedingly beautiful methods of photographing actual 

 explosions when taking place in glass tubes. Prof 

 Hopkinson 's paper dealt with a method of measuring by 

 means of a calorimeter the heat passing away from an 

 internal combustion engine in the exhaust gases. The 

 exhaust gases were cooled down in this calorimeter from 

 the exhaust temperature to atmospheric temperature, and 



NO. 1824, VOL. 70] 



therefore the amount of heat they carried away from the 

 engine could be accurately determined. He suggested that 

 it might be possible with this method to carry out thermo- 

 dynamic tests of large internal heat engines more accurately 

 than by the method hitherto adopted, in which the heat 

 given to the engine per unit of time was calculated by the 

 aid of calorimeter experiments on the combustible gases 

 employed in working the engine. The only item in the heat 

 account which was not determined in his method was the 

 small loss due to radiation. The indicator cards, or the 

 brake, gave exactly the amount of heat converted into useful 

 work, the amount of heat sent away in the jacket water 

 was easily measured, and by this new calorimeter the 

 amount of heat carried off in the exhaust gases could now 

 be determined. It was pointed out in the discussion that 

 this method of determining the heat required in a given 

 time by a heat engine by measurement of the exhaust waste 

 was analogous to that introduced by Hirn in the case of 

 steam engines many years ago. Papers by Mr. J. W. 

 Hayward on receiver drop in a compound engine, and by 

 Mr. A. H. Peake on superheated steam, concluded the day's 

 programme. 



Monday, .August 22, as usual, was devoted to the electrical 

 papers, and the proceedings opened with a paper by Mr. 

 A. A. Campbell Swinton on electricity from water power. 

 The author stated that he had been able to obtain accurate 

 statistics which showed that about 1,500,000 h.p. for 

 electrical work was now generated by water power, nearly 

 one-third of this huge total being in the United States, 

 while the total for Great Britain was only about 12,000 h.p. 

 He considered, therefore, that in all probability the real 

 amount of water horse-power devoted to this purpose at the 

 present time would be nearly 2,000,000, equivalent to a coal 

 saving of nearly 12,000,000 tons a year. After giving some 

 details of long distance transmissions abroad, he described 

 two or three systems now at work in Great Britain, and 

 then dealt with the water-power schemes with which he 

 was ofiicially connected, which had been undertaken by the 

 Scotch Water Power Syndicate. In this scheme it is 

 intended, first, to make use of Eoch Sloy, which is about 

 737 feet above Loch Lomond ; a dam will be built to raise 

 the level of the loch by about 60 feet ; the power-house is 

 to be built on the shore of Loch Lomond at Inveruglas, 

 and overhead wires will convey the electric current to the 

 industrial districts of the Vale of Leven and the Clyde. 

 The author estimated that about 50 per cent, to 58 per cent, 

 of the total energy of the water would be delivered to the 

 customers after making allowance for all the losses in the 

 pipe lines, turbines, dynamos, transmission lines, &c. The 

 company intends to employ from the start a pressure of 

 40,000 volts in view of the fact that it has powers for 

 a considerable extension of its scheme in the future, when 

 the demand for power justifies it. The total cost of the 

 Loch Slov scheme was estimated at 200,000/., and assuming 

 5000 h.p. delivered, this comes to about 40/. per h.p. every- 

 thing included, a comparatively low figure. 



The next paper, by Messrs. C. H. Merz and W. MacLellan, 

 entitled " The Use of Electricity on the North-Eastern Rail- 

 way and upon Tyneside," gave an account of the first 

 important transformation of a steam locomotive-worked 

 railway into an electric railway ; the North-Eastern Rail- 

 way Co. has adopted this latter method for the whole of 

 the suburban passenger traffic on the north side of the Tyne. 

 The company decided to use the third rail and continuous 

 current svstem, the electricity being generated as a three- 

 phase alternating current at a pressure of 6000 volts. .At 

 five substations this is converted into a continuous current 

 of 600 volts. The service given on all the line will be 

 practicallv quarter-hour trains, except on the riverside line. 

 The electrical energy is obtained from the Newcastle-on- 

 Tvne Electric Supply Co., and Parsons steam turbines, each 

 of them having a normal capacity of 7000 electric horse- 

 power, have been adopted by this company at their Carville 

 power station ; these are by far the largest steam turbines 

 at present at work in this country. The authors stated that 

 preliminary tests have shown that the steam consumption 

 would not exceed about 12 lb. per electrical horse-power 

 hour at any load between 4000 I. H.P. and 7000 I. H.P. 



Messrs. W. M. Mordey and A. G. Hansard then read a 

 paper on energy losses in magnetising iron, and described 



