CHAIN-PUMP. 



whom thought that a new kind of engine should be 

 invented and patented as a means of excluding others 

 from carrying on similar but competing operations. 

 Trevithick, always ready to invent new things, though 

 never forgetting his experience with old things, in- 

 stinctively returned to the Dolcoath engines, and re- 

 commended them as suitable for the pumping work ; 

 but finally a new design was determined on, and 

 Harvey and Co., of Hayle, received orders for the con- 

 struction, with the greatest possible dispatch, of a pump- 

 ing engine for Holland. 



This happening shortly after the writer had been 

 taken from the Bodmin school, he was desired to help 

 in the erection of this engine, and after working-hours 

 made a drawing of its original form. 



Plate XV. a, iron barge ; b, wood frame supporting 

 pump ; c, open-top steam -cylinder 3 feet diameter, 

 8 -feet stroke; c?, piston guide-wheel; e, connecting 

 rod ; /, fly-wheel ; g, cranked axle working air-pump 

 bucket ; A, connecting rod for air-pump bucket ; i, air- 

 pump ; j 9 condenser ; &, steam and exhaust nozzles ; 

 /, eccentrics working steam and exhaust valves ; m, 

 steam -pipe ; n, cylindrical boiler, with internal fire- 

 tube ; o, external brick flues ; p, chimney ; q, feed- 

 pump ; r, feed-pipe ; s, cup or rag-wheel ; t, rag-chain, 

 with iron balls ; u, pump-barrel, 3 feet diameter ; 

 v, wheel guiding balls into bottom of pump-barrel ; 

 w, launder. 



After a few successful though noisy trials, an altera- 

 tion was made in the endless chain and in the guide- 

 roller near the pump bottom. An amount of slack in 

 the chain caused the balls to knock on passing this roller 

 before entering the pump bottom. A chain having 

 long links or bars of iron of uniform length, from ball 



