THE WATT AND THE TREVITHICK ENGINES. 119 



" In 1799 Henry Clark worked as a rivet boy in Dolcoath, 

 and carried rivets to construct Captain Trevithick's new boiler, 

 said to be the first of the kind ever made. It looked like a great 

 globe about 20 feet in diameter, the bottom hollowed up like 

 the bottom of a bottle ; under this the fire was placed : a copper 

 tube attached to this bottom went around the inside of the 

 boiler, and then passed out through the side of the boiler, the 

 outside brick flues then carrying the heat around the outside 

 of the boiler and into the chimney. 



" Captain Trevithick's first plunger-pole lifts in Dolcoath 

 were put in at this time and worked by this engine. Glanville, 

 the mine carpenter, was head man over the engines when 

 Captain Trevithick was away." l 



" Charles Svvaine worked as a rivet boy in making Captain 

 Trevithick's cylindrical wrought-iron boilers for the Dolcoath 

 engine. Several of Captain Trevithick's high- pressure boilers 

 were working in the mines before that, but not made exactly 

 like the Dolcoath engine boilers. When I was a boy about the 

 year 1804, several years before I worked on the Dolcoath 

 engine boilers, I carried father's dinner to the Dolcoath 

 smiths' shop, where he worked, and used to stop and watch the 

 wood beam going up and down of Captain Dick's first high- 

 pressure steam-whim. She was not a puffer, but a puffer- whim 

 worked near by, called the Valley puffer. At that time most of 

 Captain Dick's high-pressure boilers were smallish, cast iron 

 outside, and wrought-iron tube." 2 



In 1799, shortly after the reopening of Dolcoath 

 Mine, Trevithick, jun., selected his father's second- 

 hand atmospheric engine of 1775, 3 to further improve it 

 by a new boiler of uniformly globular figure, with 

 concave circular bottom, under which fire was placed ; 

 it was of wrought iron, 24 feet in diameter, surrounded 

 by external brick flues; a large copper tube, starting 

 from the boiler bottom, immediately over the fire, 



1 Henry Clark's recollections in 1869. 



2 Working in the Valley smiths' shop, in Dolcoath Mine, in 18(59. 



3 See vol. i., p. 25. 



