i6o 



NATURE 



[August 3, 191 1 



expressly for the occasion by Mr. Norman 11. Hardy. A 

 I books and pamphlets dealing with ethno- 



ubji i i - wen alsi \ ii n flu - .hiliition of 



illustrations and literature was a greal attraction, and was 



• ■In ational value. Considering the verj few 



onnected with the congress who knew or cared 



iboul scientifii matters or methods, the scientific results 



dered is Fairlj sat isfactory. 



THE INSTITUTION OF MECHANICAL 



I VGINEERS. 



'PHE summer meeting ol tin' Institution of Mechanical 



Engineers was held at Zurich and northern Switzer- 

 land, commencing mi Monday, July -'4. In addition to the 

 meetings tor tin- reading and disi ussion ol papers, an 

 extensive programme of visits to works and hydro-electric 

 stations had been arranged, and formed an 

 important part of the meetings. ["he works visited 

 included those of Brown Boveri, Esher Wyss and Co., 

 Oerlikon Machine Works, Sulzer Brothers, and the Swiss 

 Locomotive and Machine Works. The power stations at 

 Rheinfelden, Laufenburg, Wangen, Schaffhausen, Beznau, 

 and Lontsch were also included. The institution dinner 

 was hdd on July 25. Brief notices of tin papers read are 

 given below, and a fuller abstract of a paper on high- 

 1 ressuri water-power works will appear in a later issue 



A paper on electric traction in Switzerland wax pre- 

 sented by Mr. E. Huber-Stockar, of Zurich. It may be 

 found astonishing that progress in electric traction ha- net 

 been greater in Switzerland when one considers that it is 

 necessarj to buy all the coal supply from foreign countries, 

 and that a large amount of water-power is still un- 

 developed. Further, Switzerland has had certain railways 

 electrified at a comparatively early date, and might have 

 been expected to go onward on this basis, especially as 

 applied electricity is highly developed in the country 



ally. Economy of operation is having a decisive 

 weight, and makes the problem, as it is presented, difficult. 

 The railways already electrified, or about to be electrified 

 in the near future, are such that the smoke nuisance would 

 he an almost prohibitive feature with steam traction, as 

 in the case of the Simplon tunnel, or where the capabili- 



> steam an near exhaustion, as in the case of the 

 Si Gothard Railway. There are two gauges in use, 

 '•435-metre "normal" and i-nietre "'narrow." There has 

 been but slow progress in normal-gauge railways since 

 1883, and rapid progress in narrow-gauge railways since 

 1SS7. 



1 hi author describes very fully several typical Swiss 

 railways and the methods of operation. Reference is made 

 to the valuable scientific work which has been carried out 



by the Schweizerische Studieni mission fur electrischen 



Bahnbetrieb. This society has investigated such problems 



the elucidation of the question of general railway 



electrification under s«iss conditions. The merits ol 1 1 ,. 



systems, the COSl of plant and of operation, and the 



iarison ol steam and electricity for definite lines or 

 '■1 lini -. 1 hi 1 lectrification of the St. 1 lothard 



Railway, to be carried out in the near future, has I 



well prepared b) the work of this societv. 



Railway electrification is making noteworthy rather than 

 rapid progress in Switzerland. \ d vstem, single- 



current ol low periodicitj (15) and high contact-line 



inj Ft on to 1 ai 1 ording to circum- 



is bi ing sam tioned b\ 1 xperii nee and by 

 authority. Ml electrification in Switzerland is directh con- 



d with the utilisation of water-power. The heavj 



s ol load and ii,. 1 apid • asonal vai iations in the 



fresh-water supply make desirable, and even 



■live. 



\ short survey of the praeiii.il development of the Diesel 



ngine tin to the present day was given by Mr. F. 



Schubeler, of London. It will be remembered that the 



cteristics of the Diesel principli are compression in 



•iking cylinder up to the ignition temoerature of the 



;oo lb. pi r squan inch and about looo' F.) 



and _ the use of an independent multiple-stage air-pump for 



p the pn-sure of the injection ail to 600 01 850 lb. 



xo. 2t;q. vol. 87] 



per square inch; the injection air is used for the introduc- 

 tion ol atomised ait into thi cylinder. The extreme high 

 pressures and temperatures ol the Diesel process put a 

 limit to the dimensions ol the cylinders, which will scarcer} 

 exceed 30 inches in diameter. Assuming 150 revs, per 

 min. and the ordinary Otto cycle, tin- corresponds to an 

 approximate cylinder output ol joo t" 400 horse-power. It 

 is not desirable n, havi more than six cranks; henci 

 dealing with large powers, it becomes necessary to seek 

 means of increasing the specific cylinder output. For this 

 there are thret possibilities: in bj carrying out the 

 single-acting Otto cycle machim as a double-acting one; 

 adopting the single-acting two-stroke cycle process; 



(3) by adopting tin- double-acting two-stroke cycle 1 



The first method approximately doubles the cylinder out- 

 put ; the second produces the same result, but necessitates 

 the provision of special scavenging pumps ; the third 

 theoretically quadruplicates the cylinder output, but in 

 practice about 3-4 may be secured. 



For small and medium size units the single-acting Otto 

 cycle takes the preference. Such machines have worked 

 for periods of six to eight weeks without interruption, even 

 in cement factories and mills. The two-stroke cycle shows 

 a somewhat higher consumption of fuel, amounting at least 

 to the percentage of tin- energy absorbed by the air-pump; 

 it has, however, a more favourable turning moment, and 

 guarantees better starting and better conditions for regula- 

 tion, which is sp,,ially important for direct coupling with 

 alternators. The space required is smaller, and the engine 

 is lighter and cheaper. Men are many difficulties involved 

 in the problem of the double-acting Diesel engine, and the' 

 author deprecates tin proceeding at once to the double- 

 ac nee two-stroke cycle without first gaining experience 

 with lb.' single-acting engine. Some firms have alread] 

 claimed to be able to carry out a double-acting two-stroke 

 marine engine. The results obtained with such engines 

 :ui> unknown to the author, and he feels somewhat doubtful 

 whether success has already attended such efforts. 

 Attempts have been made to build Diesel locomotives. The 

 adoption of the Diesel engine for motor-cars and eeio 

 planes does not seem to be very promising. 



Dr. Alfred Vmsler, ol Schaffhausen, described two new 

 types of transmission dynamometers. The first of these is 

 of the torsion type, and is intended for measuring the 

 power transmitted to or from high-speed machines. The. 

 dynamometer couples the shaft of the driving engine din 1 I 

 to the driven machine, and eonsi-is essentially of a shaft 

 the angle of twist of which gives a measure ol the torque. 

 To measure the angle of twist three- discs ,i r( . used, one 

 fixed to one- .nd of the shaft and tin- other two fix. d 

 to the oilier .rid \ transparent celluloid rim is attached 



to the lirs( disc, and lias divisions cut on il ; each of the 



other two discs I as a radial slit. The scale divisions are 

 strongly illuminated, and max- be clearly read through the 

 slits when the shall is running. An impression is given 

 to the eve even revolution, and at high speeds these 

 impressions becomi a continuous stationary image. 



The other type of dynamometer is intended fm use with 

 slow-running machines of variable resistance. 'Inn pulleys 

 are placed clos. together on a common shaft, one 

 tixicl to the shaft and the Other pulley runs loos.. II. 

 pulleys .ue ... ol two cylinders fitted with 



pistons and charged with oil. The drive from the source 

 ol power is ci d to one pulley bv bi It . and the 



mac bine under test is driven by belt from the other pulley. 

 In operation, tie oil in the cylinders i- put under pressure 

 corresponding to the torque being transmitted. The shaft 

 is hollow, and serve- to make communication between the 

 cylinders and a pressun 1 dings of which give 



a measut e ol the ti rqui 



A paper on rack-railway locomotives of the Swiss moun- 

 tain railways was read b\ Mr. T. Weber and Mr. S. \bt, 

 ol Winterthur. Switzerland lias a total of 120 steam loco- 

 motives, a, w.'ll as 1; electrii 1 motives and 



coaches arranged for working with rack Sear. The total 

 length of the rack railways is S7 miles. The whole ol the 

 svstcms of racks whit h are in use havi b.en designed in 

 Switzerland. Tin am system has been most adopted, and 

 consists of flat-toothed plates, of which two or three. 

 ling to the tractive power, are bolted together on 

 chairs in such a way that the tooth of one plan m regard 



