THE WATT AND THE TREV1THICK EX< JINKS. 149 



which was still deferred for further consideration, even 

 with the limited pressure of 25 Ibs. to an inch ; so the 

 large Watt pumping engines were doomed for another 

 four or five years to struggle through their work with 

 low-pressure steam, though at that time Cook's Kitchen 

 high-pressure expansive condensing whim-engine had 

 been for years at work close by. 



The shareholders professed to have fear of explosion ; 

 but party-feeling and ignorance were the real causes of 

 opposition, for working men had no dread of the new 

 engines, while influential men leaned toward Watt's 

 old-fashioned plans. 



. This fear of Trevithick's expansive plans and high 

 steam is the more surprising, because at that time a 

 new boiler was required for the Watt 6 3 -inch cylinder 

 pumping engine and Trevithick's cylindrical tubular 

 boiler could be made for one-third less cost than 

 the Watt waggon boiler, thus saving 300., and in 

 addition he promised to apply the higher pressure of 

 steam to the Watt engine without any change in its 

 parts or expenditure of money, and make it set in 

 motion at the commencement of the stroke the 200 tons 

 of pump-rods, the momentum of which would, with the 

 expansion of the steam, when shutting it off soon after 

 the first start in the movement of each stroke, carry it 

 through to the end ; and he practically compares this 

 advantage from hoarded momentum in the pumping 

 engine with his experience of the fly-wheel of the rolling- 

 mill expansive engine in Wales. 



The whim-engine with a fire-tube 2 feet 3 inches in 

 diameter used 84 Ibs. of coal per hour ; and at that rate 

 one cylindrical boiler 30 feet long, 8 feet in diameter, 

 with internal fire-tube 5 feet in diameter, would supply 

 steam for Watt's 63-inch cylinder; but in place of it 



