PoLK STKAM-KXGINE. 01 



house, it was so full of steam and noise; we could hear the 

 steam-puffer roaring at St. Ertb, more than three miles off." 



By the end of January, 1816, the engine was ready 

 for work, and after ten days of experience, he thus 

 described the result : 



" MR. DAVIES GiDDY, M.P., " PENZANCE, llth February, 1816. 



Sir, I was unwilling to write you until I had made a 

 little trial of the Herland engine. It has heen at work about 

 ten days, and works exceedingly well ; everyone who has seen it 

 is satisfied that it is the best engine ever erected. It goes 

 more smoothly than any engine I ever saw, and is very easy and 

 regular in its stroke. It's a 33-inch cylinder, 10J-feet stroke. 

 We have driven it eighteen strokes per minute. In the middle, or 

 about two-thirds of the stroke, it moved about 8 feet per second, 

 with a matter in motion of 24 tons ; and that weight returned 

 thirty-six times in a minute, with 2 bushels of coal per hour, 

 This of itself, without the friction, or load of water, is far more 

 duty than ever was done before by an engine. I found that it re- 

 quired about 80 Ibs. to the inch to work the engine the first twelve 

 hours, going one-third expansive, twelve strokes per minute, 

 IGJ-feet stroke, with 21 bushels of coal. The load of water 

 was about 30,000. This was occasioned by the extreme friction, 

 the plunger-pole being turned, and the plunger-case bored, to 

 fit so nicely from end to end, that it was with great difficulty 

 we could at all force the plunger-pole down to the bottom of the 

 plunger-case. This is now in a great degree removed, and since 

 we went to work we have thrown into the balance-box 4 tons of 

 balance, and it would carry 3 tons more at this time. We must 

 have carried that load in friction against the engine, therefore, 

 if you calculate this, you will find it did an immense duty, going 

 twelve strokes per minute, 10-^-feet stroke, with 2 bushels of coal 

 per hour. The engine is now working regularly twelve strokes per 

 minute, with 60 Ibs. of steam, 10^-feet stroke, three-quarters of 

 the stroke expansive, and ends with the steam rather under 

 atmosphere strong, with considerably within 2 bushels of coal 

 per hour. I would drive her faster, but as the lift is hanging in 

 the capstan rope under water, they are not willing to risk it. I 



