160 THE WATT AND THE TREVITHHJK ENGINES. 



engineers that put her up. The 76-inch cylinder came from 

 Wales. The big beam was cast at Perran Foundry in 1815; 

 you can see the name and date upon it now. The boiler and 

 the gear-work were made in the mine. The exhaust-valve is 

 exactly as when it was put in, worked by a rack-and-tooth 

 segment. The equilibrium valve is unchanged, except that the 

 rack is taken out and a link put in. 



" The steam-valve was taken out soon after she went to work, 

 and the present double-beat valve was put in ; it is the first of 

 the kind I ever saw. Some were made before that time with 

 a small valve on the top of the big one, that opened first, 

 to ease the pressure. 



"John West 1 fitted up the valve-gear in the mine with the 

 expansive tappets, the same as when she stopped a month or 

 two ago, and the same as the present new one has. 



" Captain Dick's cutting off his strong steam at an early part 

 of the stroke, used to make the steam-valve strike very hard ; so 

 the new plan valve, with a double beat, was put in ; that must 

 have been about 1816 'or 1817 ; and the valve and expansive 

 horn for working were just exactly like what they have put 

 into the present new engine in 1869. She was the engine that 

 showed them how to fork the water, and burn only half the coal. 



U I worked in this mine the old atmospheric engines, and then 

 Boulton and Watt ; and then Trevithick's boilers in Boulton and 

 Watt; and then Trevithick's boilers and engine; and now I 

 come every day to the new engine, though I can't do much. 

 They give me 3*5s. a month ; and my name is William Pooly, 

 Dolcoath, 1869." 



Three years ago (in 1869), when the writer entered 

 the old engine-house in which Watt's 63-inch cylinder 

 double had been erected in 1780, adjoining the old 

 walls that then enclosed that early Newcomen 45-inch 

 cylinder Oarloose engine, re-erected by Trevithick, 

 sen., in 1775 in Bullan Garden portion of Dolcoath, 



1 Three Wests, all skilful mechani- 

 cal engineers, were employed at that 

 time in Dolcoath, all of them known 

 to the writer, who thinks the double- 



beat valve was the handiwork of John 

 West, not related to Trevithick's 

 partner. 



