356 TUBULAlt BOILEK, SUPERHEATING STEAM, 



A further proof of the indirect public gain from the 

 use of Trevitl lick's return-tube boiler over a period of 

 thirty years is their having supplied high-pressure ex- 

 pansive steam in the first experiments made with such 

 steam by the Admiralty, at whose request Mr. Rennie 

 and others examined the duty of the Cornish high- 

 pressure expansive engine, and Captain King, R.N., 

 in charge of the Admiralty Department at Falrnouth in 

 1830, gave an order to Harvey and Co. to construct 

 high-pressure steam-boilers for the Government vessel 

 'Echo'; in 1831 the machinery was put on board 

 the ' Echo ' in the Government Dockyard at Plymouth, 

 and included three of Trevithick's return-tube boilers, 

 made of wrought iron, each 5 feet 6 inches in diameter 

 and 24 feet long, with internal return fire-tube 2 feet 

 2 inches in diameter. The fire-place end of the boiler 

 was 6 feet 9 inches deep by 5 feet 6 inches wide, to 

 give room for the fire-place and ash-pit. The steam 

 pressure was 20 Ibs. on the inch above the atmosphere, 

 worked by double-beat valves, 6 inches in diameter, 

 with expansive gear. 



This new machinery was fixed under the superin- 

 tendence of the writer, after which the Government 

 engineers took charge of the vessel, and the writer who 

 had, as the mechanic in charge, worked like a slave, 

 though receiving but Is. 6<i. a day and expenses, was 

 not invited to take any part in the experimental trials, 

 nor ever heard of the result except in the ordinary 

 rumours of Admiralty bungling on board the 'Echo/ 



Those boilers were similar to the Trevithick boiler 

 that had served the locomotive in Newcastle and else- 

 where from 1801 to 1828, the first steamboat experi- 

 ments in England, in Scotland, and in America, and 

 the numerous high-pressure engines then at w r ork. 



