POLE STEAM-ENGJ N K. 69 



CHAPTER XIX. 



POLE STEAM-ENGINE. 



in the autumn of 1810 Trevithick returned to 

 Cornwall, the experience of ten busy years had esta- 

 blished the practicability and usefulness of the high- 

 pressure engine. The principles of the invention were 

 now to be applied on engines of the largest size. 



In 1811, the late Captain S. Grose, a young pupil of 

 Trevithick's, was employed to erect at Wheal Prosper 

 Mine, in Gwythian, the first high-pressure steam pole 

 condensing engine. It was placed immediately over 

 the shaft and pump-rods, requiring no engine-beam. 

 The air-pump, feed-pump, and plug-rod were worked 

 from the balance-bob. The pole was 16 inches in dia- 

 meter, with a stroke of 8 feet. The boilers were two 

 wrought-iron tubes, 3 feet in diameter and 40 feet 

 long. The fire was external. Shortly after Captain 

 H. A. Artha erected several of those pole-engines for 

 Trevithick. The drawing shows the simplicity of parts 

 of this highly expansive steam-engine, beginning the 

 up-stroke with steam of 100 Ibs. to the inch above the 

 atmospheric pressure, expanding it during the stroke 

 down to a pressure of 10 Ibs., and then condensing 

 to form a vacuum for the down-stroke. It cost 750 

 guirieas ; 



The drawings of this expansive pole condensing en- 

 gine are from the dimensions given by Captain Grose 

 who erected it, and by Captain Artha who knew it well. 



