504 REPORT — 1881. 



visit Nantes, where for eighteen months tramcars had been driven by 

 compressed air, carried on the cars themselves, coupled with an extremely 

 ingenious arrangement for overcoming the difEculties commonly attendant 

 on the use of compressed-air engines. This consists in the provision of 

 a cylindrical vessel half filled with hot water and half with steam at a 

 jDressure of 80 lbs. on the square inch ; the compressed air on its way 

 from the reservoir to the engine passes through the water and steam, 

 becoming thereby heated and moistened, and thus all the danger of 

 forming ice in the cylinders is prevented and the pistons and slides are 

 susceptible of good lubrication. These cars, which start every ten minutes 

 from each end, make a journey of of miles, and have proved to be a 

 commercial and an engineering success. I believe, moreovei-, that the 

 system is capable of very considerable improvement. Then there is, 

 although not much used, the transmitting of power by means of long 

 steam pipes. There is also the transmission hydraulically. This may be 

 carried out in an intermittent manner, so as to replace the reciprocating 

 flat rods of old days. That is to say, if two pipes containing water are 

 laid down, and if the pressure in those pipes at the one end be alternated, 

 there will be produced an alternating and a reciprocative effect at the 

 other end, which may be employed to give motion to pumps or other 

 machinery. There is also that thoroughly well-known mode of trans- 

 mission hydraulically for which the engineering woi4d owes so much to 

 our President. We have, by Sir William Armstrong's system, coupled 

 with his accumulator, the means of transmitting hydraulically the power 

 of a central motor to any place requiring it, and by means of the 

 principal accumulator, or if need be by that aided by local accumulators, 

 a comparatively small engine is enabled to meet very heavy demands 

 made upon it for a short time. I think I am right in saying that at 

 the ordinary pressure which Sir William Armstrong uses in practice, 

 VIZ., 700 lbs. to the square inch, one foot per second of motion along an 

 inch pipe would deliver at the rate to produce one horse-power. There- 

 fore a 10-inch pipe with the water travelling at no greater pace than 3 

 feet in a second would deliver 300 horse-power. This 300 horse-power 

 would, no doubt, be somewhat reduced by the loss in the hydraulic engine, 

 which would utilise the water, but the total energy received would be 

 equivalent to producing 300 horse-power. Such a transmission would 

 be effected with an exceedingly small loss in friction in transit; I believe I 

 am right in saying, that a 10-inch pipe a mile long would not involve 

 much more than about 14 lbs. or 15 lbs. differential pressure to propel the 

 water through it at a rate of 3 feet in a second. If that be so, then with 

 700 lbs. to the inch, the loss under such circumstances would be only 2 

 per cent, in transmission. There is no doubt that this transmission of 

 power hydraulically has been of the greatest possible use. It has 

 enabled work to be done which could not be done before. Enormous 

 weights are raised with facility wherever required, as, by the aid of 

 power hydraulically transmitted, it is perfectly easy for one man to 

 manage the heaviest crane. Moreover, as I have said in other places, 

 this system, which we owe to Sir William Armstrong, has gone far to 

 elevate the human race, and it has done so in this manner. So long as 

 it is competent for a man to earn a living by a mere unintelligent exercise 

 of his mutcles he is very likely so to do. You may see in the old London 

 Docks the crane-heads covered by structures that look Hke paddle-boxes ; 

 if you go up to them you will find, I am glad to say, there is nothing now 



