430 



NATURE 



[September i, 1892 



cidedly a pleasant innovation, the Saturday morning's meeting 

 being by no means popular. Whether there be few or many 

 papers, it seems impossible to get through a sitting in a short 

 time, as there are always one or two speakers, at any rate, who 

 will spin the discussions out, so that those who are obliged to 

 stay to the end have no time to get lunch before starting on the 

 excursions. Section G made a trip to Glasgow on the Saturday, 

 and were rewarded by perhaps the finest exhibition of marine 

 machinery ever collected in a single installation. This comprised 

 the propelling engines of one of the pair of enormous vessels the 

 Fairfield Company are building for the Cunard line. The 

 engines were erected in the shop, and one was enabled to get a 

 fair prospective of their grand proportions, such as will be 

 impossible when they are confined to their natural position on 

 shipboard. 



On the section again assembling on the Monday following the 

 first business was the reading of the report of the committee 

 appointed to consider "The Development of Graphic Methods 

 in Mechanical Science." This report had been prepared by 

 Prof. Hele-Shaw, of Liverpool, who must have spent a vast 

 amount of pains in compiling the very bulky document, which 

 was read in abstract. The bibliography should be especially 

 valuable. This is the second report that has been presented by 

 the committee, and, we believe, the subject is to be further in- 

 vestigated. The use of graphic methods is far less common 

 with engineers than it might be with advantage, and the matter 

 is one which the Mechanical Section of the British Association 

 is especially fitted to deal. 



Mr. Preece next read two papers, in the first of which he took 

 the municipal authorities to task for causing stack pipes to be 

 disconnected from the drains, and thus depriving these natural 

 lightning-conductors of their lead to earth. If Mr. Preece's 

 prognostications are fulfilled there will be a great increase in 

 casualties from lightning when the new legislation comes widely 

 into effect, unless some other means be taken to make connection 

 between stack pipes and earth. Mr. Preece did not read his 

 second paper, but contented himself with saying a few words to 

 signify its scope. Its title was " The use of secondary batteries 

 in telegraphy." For the past seven years secondary batteries 

 have been used at the Post Office to supply current to two large 

 groups of circuits, one group consisting of i lo single needles, 

 and the other of lOO Morse inkers and sounders. 



Mr. Gisbert Kapp next read a practical and interesting paper 

 on " Power Transmission by Alternating Current," describing 

 an installation which has been carried out at Cassel. In that 

 town the water supply is a municipal undertaking, the source 

 being at a distanee of four miles or so from the town. In the 

 summer a large quantity of water is used, and for this reason 

 a certain amount of pumping has to be done. The pumps are 

 worked by turbines. In the winter the existing natural gravi- 

 tation supply is sufficient, and the turbine pumps are, therefore, 

 not required. It is, of course, in winter that the chief demand 

 for light occurs and then the turbines, in place of being idle, are 

 used for driving dynamos. Mr. Kapp explained by means of 

 diagrams the manner in which a storage system is carried out so 

 that the turbines may be kept constantly at work. The power 

 is transmitted by a single phase alternating current from the 

 generating station to two sub-stations at Cassel. At one of the 

 sub-stations there is a battery which is charged during the hours 

 of light load, to be in turn drawn upon during the time of heavy 

 load. Each of the two sub-stations contains a transformer so that 

 the distribution is by continuous current, whilst between the 

 generating station and the sub-stations the current is alternating, 

 the pressure being 2000 volts. The installation was the work 

 of Mr. Oskar von Millar, Mr. Kapp designing the alternators. 

 The author gave a good many details of the arrangement of 

 which the above is an outline. In the discussion which followed 

 an interesting point was raised as to the effect of putting the 

 alternators out of step. The author said that in the present in- 

 stance he had no hesitation in putting the load on suddenly and 

 no effect followed, but if the load were suddenly taken off, the 

 machine would start howling in a frightful manner until it again 

 got in synchrony. This was alarming at first, but not otherwise 

 hurtful. 



Mr. E. H. Woods next read a paper in which he gave par- 

 ticulars of a new design of electric locomotive. The driving 

 wheels are placed horizontally, the necessary grip being, we 

 understood, obtained by springs, which press the pairs of wheels 

 against a central rail. There is an ingenious device for points 

 and crossings which was illustrated by a model. The motor is 



to be kept running continuously, the grip of the wheels being 

 released when the train is stopped, the power then be absorbed 

 by frictional brakes. The relative value of this device naturally 

 depends on the length of the stoppage. Mr. Kapp and Prof. 

 Forbes both spoke on the question ofcontinuous running motors, 

 neither appearing to look with favour on the device, 



Monday is generally devoted wholly to electrical engineering, 

 but on this occasion the papers on the subject were not suffi- 

 ciently numerous to fill up the sitting. The rest of the day 

 was, therefore, filled up with papers of a miscellaneous nature. 

 The first of these was a contribution by Lieut. W. B. Basset, 

 R.N., who described a very ingenious coin-counting machine 

 which has been recently placed in the Royal Mint. It would 

 be impossible to describe this apparatus without the aid of 

 drawings; but it may be stated that 3,000 coins can be counted 

 in a minute, or one ton in three-quarters of an hour. The 

 coins are made to move along a channel of such a size that only 

 one can pass at a time. They are forced along by means of two 

 driving wheels, actuated by an electric motor. At the lower 

 end of the channel is a wheel with notches in its rim, the notches 

 being of a shape that the coins just fit into them. The wheel is 

 made to turn by the coins as they are forced forward, the action 

 being comparable to that of a rack and pinion, the rack being 

 formed by the procession of coins pushed forward by the driving 

 wheels. The counting wheel must necessarily pass a coin for 

 each notch or tooth it advances, and as a given number of teeth 

 always go to a revolution, an accurate record is obtained. The 

 machine in the Mint is arranged to count pence, half-pence, 

 piastres, half-piastres, and Hong Kong cents. It counts on an 

 average over two million coins a month without error. 



Mr. Killingworth Hedges next read a paper on " Anti- 

 Friction Material for Bearings used without Lubrication." 

 This referred chiefly to a bearing composed of finely-powdered 

 carbon mixed with steatite, which the author had found valuable. 

 He referred to the advantages of non-lubricated bearings, such 

 as saving in labour, cost of oil, and cleanliness. In the discus- 

 sion which followed. Professor Unwin well summed up the 

 question by saying that though there might be a higher co-effi- 

 cient of friction with a non-lubricated bearing, manufacturers 

 could generally well afford a small additional expenditure of 

 power in order to be free from the defects of oiled bearings. 



A paper by Mr. B. H. Thwaite on high-pressure boilers, 

 which does not call for notice here, was the last read on this 

 day. 



The last day on which Section G sat was Tuesday, the gih 

 inst., when the proceedings were opened by a paper by Mr. 

 D. A. Stevenson, entitled "Petroleum Engines for Fog 

 Signalling," being read. The paper, which was read by Mr, 

 C. A. Stevenson in his brother's absence, stated that the 

 maximum number of hours of duration of fog in Scotland was 

 395 per annum. For sounding the siren various motors are 

 available, which may be actuated by the waves or tides, manual 

 labour, clockwork, steam, hot air, gas, or oil. The author states 

 that the oil engine is the be.-<t for the purpose. He slates, how- 

 ever, that all fog signals which appeal to the ear must be of 

 an unreliable nature, and he would prefer some method, such as 

 had been proposed by Mr. C. A. Stevenson, in which an electric 

 conductor is laid down off a coast, so as to act on an instrument 

 attached to each vessel. It would have added to the value of 

 the paper had sufficient detail of this device been given to afford 

 the meeting an idea of its general principle. As the description 

 stands we quite fail to see how a useful result could be brought 

 about. An interesting discussion followed the reading of this 

 paper, in which the chief feature was the speech of Mr. A. R. 

 Sennelt, who pointed out that water is a better medium than air 

 for conveying sound, and reminded the meeting that sound was 

 very liable to be deflected by "acoustic clouds." Tyndall 

 found that the presence of such clouds reduced by one-third the 

 distance at which a given sound could be otherwise heard. Mr. 

 David Cunningham, the harbour engineer at Dundee, gave a 

 remarkable example of the influence of acoustic clouds. He 

 had gone out in a steam yacht when the siren was in operation. 

 At a distance from it of hair a mile the sound was not to be 

 heard, but when they had steamed four miles the siren was 

 again audible. It had been sounding the whole time. To 

 return to Mr. Sennett's remarks, that speaker said he proposed 

 taking advantage of the sound-carrying power of water in the 

 following way. He would have the siren, which indicated a 

 danger, submerged in place of being in the air. It would be 

 arranged to give off a certain note. In each ship there would 



NO. I 192, VOL. 46] 



