TRANSACTIONS OF SECTION G. 851 



method, not now much used, by which the cylinder condensation can be directly 

 combated. Thirty years a^o superheating the steam was adopted with very con- 

 siderable increase of economy. It is likely that it was thought by the inventor of 

 superheating that an advantage would be gained by increasing the temperature 

 range. If so, his theory was probably a mistaken one." For the cooling action of the 

 cylinder is so great that the steam is reduced to saturation temperature before it 

 has time to do work ; but the economy due to superheating was unquestionable, 

 and was very remarkable considering how small a quantity of heat is involved in 

 superheating. The heat appears to diminish the cylinder wall action so much as 

 almost to render a jacket unnecessary. The plan of superheating was abandoned 

 from purely practical objections, the superheaters then constructed being dangerous. 

 Recently superheating has been tried again at Mulliouse by M. Meunier, and his 

 experiments are interesting because they are at higher pressures than in the older 

 trials and with a compound engine. It appears that even when the superheater 

 was heated by a separate lire there was an economy of steam of 25 to 30 per cent, 

 and an economy of fuel of 20 to 25 per cent., and four boilers with superheating 

 were as efficient as five without it. 



It may be pointed out as a point of some practical importance that if a 

 trustworthy method of superheating could be found, the advantage of the triple 

 over the compound engine would be much diminished. For marine purposes the 

 triple engine is perfectly adapted. But for other purposes it is more costly than 

 the compound engine, and it is less easily arranged to work efficiently with a 

 varying load. 



There does not seem much prospect of exceeding the efficiency attained already 

 in the best engines, though but few engines are really as efficient as they might be, 

 and there are still plenty of engines so designed that" they are exceedingly unecono- 

 mic?.l. The very best engines use only from 12 to 1.3 lb. of steam per indicated 

 horse-power hour, having an absolute efficiency reckoned on the indicated power 

 of 16 per cent., or, reckoned on the ertective power, 13 per cent. The efficiency, 

 including the loss in the boiler, is only about 9 per cent. But there are internal 

 furnace engines of the gas-engine or oil-engine type in which the thermal efficiency 

 is double this. 



In his interesting address to this Section in 1878, Mr. Easton expressed the 

 opinion that the question of water-power was one deserving more consideration 

 than it had lately received, and he pointed to the variation of volume of llow 

 of streams as the principal objection to their larger utilisation. Since that time 

 the progress made in systems of transporting and distributing power has given 

 quite a new importance to the question of the utilisation of water-power. There 

 seems to be a probability that in many localities water-power will, before long, be 

 used on a quite unprecedented scale, and under conditions involving so great 

 convenience and economy that it may involve a quite sensible movement of 

 manufacturers towards districts where water-power is available. 



If we go back to a period not very distant in the history of the world, to the 

 middle of the last century, we reach the time when textile manufactures began to 

 pass from the condition of purely domestic industries to that of a factory system. 

 The fly-shuttle was introduced in 1750, the spinning-jenny was invented in 17G7, 

 and Crompton's machine only began to be generally used in 1787. It was soon 

 found that the new machines were most suitably driven by a rotary motion, and 

 after some attempts to drive them by horses, water-power was generally resorted 

 to. In an interesting pamphlet on the Rise of the Cotton Trade, by John 

 Kennedy, of Ardwick Hall, written in 1815, it is pointed out that the necessity 

 of locating the mills where water-power was available had the disadvantages 

 of taking them away from the places where skilled workmen were found, and 

 from the markets for the manufactured goods. Nevertheless, Mr. Kennedy states 

 that for some time after Arkwright's first mill was built at Cromford all the 

 principal mills were erected near river falls, no other power than water-power 

 having been found practically useful. 'About 17P0,' says Mr. Kennedy, 'Mr. 

 Watt's steam-engine began to be understood, and waterfalls became of less value. 

 Instead of carrying the workpeople to the power, it was found preferable to place 

 the power amongst the people.' 



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