September i, 1892] 



NATURE 



429 



MECHANICS A T THE BRITISH ASSOCIA TION. 



CECTION G had a good meeting at Edinburgh this year, 

 *^ there being a great improvement on last year's gathering at 

 Cardiff. On the members assembling on Thursday morning 

 the fourth inst. in the old University Buildings the first business 

 was naturally the Presidential address. Prof. W. C. Unwin, 

 F.R.S., who this year occupied the chair, is eminently fitted to 

 preside over the Mechanical Science Section. His knowledge of 

 the scientific side of mechanics is well known, and his past 

 experience in the region of practical mechanics puts him 

 thoroughly in touch with the many engineers who frequent the 

 section. His address, which we have already printed, was 

 listened to by a large audience, the theatre being quite full. 

 The vote of thanks to the President for his address was moved 

 by Lord Kelvin and seconded by Mr. Deacon, of Liverpool. 



The first paper on the list was a contribution from Mr. James 

 Dredge and Mr. Robert S. McCormick on the American 

 Exhibition, which is to be held next year in Chicago. The 

 paper gave a good general description of the coming show from 

 the engineer's point of view ; but the subject is one that offers 

 better scope for the members of Section F. It is manifestly 

 impossible to give anything like a good engineering description 

 within the limits of a short paper, whilst the advantages and 

 disadvantages of exhibiting might well have supplied a theme 

 for discussion in the Economic Section. In fact, the discussion 

 which followed the reading of the paper turned wholly on this 

 branch of the subject. The next three papers were of a sanitary 

 nature. Prof. George Forbes and Mr. G, Watson, of Leeds, 

 both dealt in the disposal of town refuse, the former bringing in 

 the electrical lighting of Edinburgh as a part of his scheme. 

 Mr. Forbes points out that in the electric lighting of towns the 

 demand for power is but for a few hours daily. With no system 

 of accumulators, or power storage, this necessitates a large plant 

 compared to that which would suffice if the demand could 

 be made continuous. The author, therefore, proposes to use 

 Arthur's Seat as an accumulator, by forming a reservoir on its 

 summit, and into this reservoir water would be pumped con- 

 tinuously. The head of water thus obtained would be used 

 for working turbines, which would be of sufficient power for the 

 maximum demand. There would thus be a gain through 

 keeping the steam engines constantly at work, smaller engines 

 could be used, and there would not be the loss incidental to 

 raising steam or keeping the boiler fires banked. The great 

 feature of the scheme, however, is to use the dust-bin refuse of 

 the city as fuel for raising steam. The author would erect 

 destructors, and the waste heat from these would be passed 

 through the boiler flues. Prof. Forbes quoted figures in support 

 of his contention that the scheme is practicable, and he instanced 

 what has been done at Southampton, and elsewhere, in the 

 matter of using domestic refuse for steam-generating purposes. 

 We are not able to criticise the details put forward, but we may 

 venture to say that, if the scheme can be worked out practically, 

 engineers will have put before them an example of the use of 

 waste material which many have not hitherto considered capable 

 of being so successfully applied. The author stated that the 

 refuse of a city, if properly burnt, would generally supply suffi- 

 cient heat to raise the steam necessary for the electric lighting 

 required. That is a very satisfactory adjustment of supply and 

 demand, and if Prof. Forbes cm show municipal engineers how 

 to put it in practice he will have rendered a most important 

 service for which every one should be devoutly grateful. After 

 disposing of the particular scheme for the refuse destruction and 

 electric lighting of Edinburgh, the author gave some interesting 

 particulars of that which has already been done in this country 

 in the matter of burning town refuse. 



The next paper was contributed by Mr. G. Watson, of Leeds, 

 and was an excellent treatise on the refuse-destructor question. 

 The various types of apparatus which have already been Jput in 

 use were illustrated by wall-diagrams, and the chief points in 

 their construction were explained. Mr. Watson is of opinion, 

 and he supported his opinion by results of actual experience, not 

 only that dust-bin refuse can be burned in a properly constructed 

 destructor without nuisance, but that the waste heat can be used 

 for raising steam ;or, if required, that dust-bin refuse and sewage 

 sludge, containing 90 per cent, of moisture, may be satisfactorily 

 burnt together, the Horsfall destructor being, apparently, 

 particularly suitable for the purpose. The whole subject is one 

 of great and growing importance. It is to be regretted that both 

 these papers were not printed and distributed previously, so that 



NO. II 92, VOL. 46] 



a thorough criticism of the various points raised might have been 

 made during the discussion. 



A paper by Mr. R. F. Grantham, on the absortpion and 

 filteration of sewage was next read. The author gave accounts 

 of many examples that have been carried out in different parts of 

 the world, and of experiments made in this connection. Mr. 

 Grantham is of opinion that the Maplin and Foulness Sands at 

 the mouth of the Thames might be used to advantage for treat- 

 ment of the sewage of London. 



The next paper was of a different character. It was by Mr. 

 G. F. Deacon, and contained a description of the work the author 

 had carried out in shield tunneling in loose ground whilst con- 

 structing the Vyrnwy Aqueduct tunnel under the Mersey. The 

 work, as is generally known, was one of remarkable difficulty, 

 and the manner in which the various obstacles to its completion 

 were overcome affords a valuable lesson for engineers. 



Mr. D. A. Stevenson next read a paper in which he advo- 

 cated the construction of a ship canal between the Forth and the 

 Clyde. The scheme included a tunnel high enough to pass the 

 masts of big vessels, and locks sufficiently large to take in ocean- 

 going steamers. The estimated cost is ;^8,ooo,ooo. After a 

 short discussion of this paper the section adjourned. 



On the next day, Friday, the 5th inst., the first busine-s was 

 the reading of a: paper by Mr. D. Cunningham, in which he 

 described a mechanical system for the distribution of parcels. 

 The device was illustrated by means of a working model, with- 

 out the aid of which, or drawings of the mechanism, it would 

 be difficult to make the principle understood. 



Mr. Alexander Siemens next described two electric locomotives 

 which his firm had recently supplied to the City and South Lon- 

 don Railway. - These, as it is proper they should, have been 

 more successful in their working than the engines originally 

 placed on the line. The armatures of the motors are wound on 

 the axles, so that no gearing is required. According to dia- 

 grams displayed, the efficiency varied between about 90 and 94 

 per cent. Each locomotive, fully equipped, weighs 13^ tons, 

 and the weight of the train of carriages is about 21 tons, without 

 passengers. The weight, w? believe, is considerably greater 

 than in the original locomotives used on the line, and this is 

 undoubtedly an advantage. Mr. J. H. Greathead, Professors 

 Silvanus Thompson, and G. Forbes took part in the discussion ; 

 in replying to which the author attributed the success of the 

 motors to large armatures and large field magnets. Prof. 

 Silvanus Thompson stated that Messrs. Mather and Piatt, of 

 Manchester, are now building an electric locomotive which is to 

 be more powerful than anything that has gone before. 



Hydraulics next occupied the attention of the section, Messrs. 

 F. Purdon and H. E. Walters describing an interesting tide- 

 motor which they have devised and constructed. The machine 

 takes the form of a floating barge or flat, which is moored 

 athwart the tide-way. There are two drum^ placed some dis- 

 tance apart, and on these drums a chain is made to travel 

 by floats attached to it, which floats project downwards into 

 the water, and are carried along on the forward stroke by 

 the action of the tide, whilst the return stroke is made in the 

 air. As the flat is moored athwart the stream— in order to 

 utilize the greatest possible area of the current — and as the chain 

 travels fore and aft, guides are used to conduct the water in 

 the proper direction to actuate the floats or paddles. The 

 guides also concentrate the stream. These are roughly the 

 fundamental features of the design, further details of which 

 we are unable to give through limits of space. The machine, 

 however, is very interesting, and is perhaps one of the most 

 promising and best worked-out motors of its kind. There 

 appears now to be better prospect for inventions of this nature 

 than heretofore, on account of the facilities offered for transport 

 of power by means of electricity. It is always a tempting pro- 

 blem to try to use some of the vast store of energy running to 

 waste in the tides, although the question is one beset with 

 practical difficulties that have been sufficient hitherto to make 

 tide-motors very scarce. 



A paper by Mr. Pearsall, in which he described a new 

 arrangement of hydraulic ram, which he had made, was next 

 read ; Prof. Blyth described a new form of windmill on the 

 principle of the Robinson cup anemometer ; and Mr. G. R. 

 Redgrove having read a contribution on Levavasseur's flexible 

 metallic tubing, the second day's proceedings were brought to a 

 close. 



The next sitting was held on the following Monday, the 

 section not meeting on Saturday. The arrangement was de- 



