TIIK WATT AND THE TREVITHICK ENGINES. 161 



an old man sat near a small window in a recess in 

 the thick wall of the engine-house, within reach of 

 the gear-handles of the Jeffrie and Grribble 76-inch 

 cylinder engine that Trevithick, jun., had erected in 

 1816 on the foundations of the removed Watt engine; 

 he held in one hand a portion of slate from the 

 roof, and in the other an old pocket-knife, one- 

 half of the blade of which had been broken off, leaving 

 a jagged fracture, with which he made the figures of 

 some calculation on the rude slate ; on his nose rested 

 the brass frame of a pair of very ancient spectacles, with 

 horn glasses. He answered the writer's question by, 

 "Yes, I am William Pooly; I worked this engine, and 

 the other engines before it the great double and the 

 little Shammal working out of the same shaft ; and I am 

 seventy-four years of age. The 63 single worked upon a 

 shaft up there ; she was called Wheal Gons." That old 

 man, still living, had worked in Dolcoath Mine one of the 

 first steam-engines of -NeWcomen; the 45-inch, modified 

 by Trevithick, sen. ; then the 63-inch double of Watt ; 

 and, finally, the high-pressure engines of Trevithick, 

 jun. ; he saw the open-top cylinders, atmospheric of 

 Newcomen, in the Shammal 45-inch and Wheal Gons 

 63-inch, with their wooden beams with segment-headed 

 ends, moving in rivalry with the Watt 63-inch double, 

 with cylinder-cover and parallel motion ; he saw the two 

 former engines, as altered by Trevithick, jun., using the 

 higher steam from the globular boiler on which Henry 

 Clark worked in 1799, when "there used to be great 

 talking about different boilers, and a boiler of Captain 

 Trevithick's worked with higher steam than the others; 

 and the waggon boiler of Watt, that had just been re- 

 paired, was discarded and cut up ; " thus described by 

 Trevithick, " the fire-place is 22 feet from fire-door to 



VOL. II. M 



