xin 
averaged 17°6* millions per bushel, or between 8:1 and 39°5 per 
hundred weight of coal used. : 
Boulton and Watt did not obtain the lead in Cornwall with- 
out strenuous opposition from resident engineers and proprietors 
of mines.f In course of the numerous contests in which they. 
* “Tn May, 1798, returns were made by the agents in various mines, 
of all the particulars respecting twenty-three engines, from which I then 
deduced their respective duties.” 
Diameter Dury — 
cae Ahly of Cylinder ; Per (84 1bs.) | ber wt, of Observations. 
z inches. - bushel (Glam. 
of Coal. 
1 Single ... 20: 10,015,000 | 13,353,333 
9 Be ae 21- 16,385,000 | 21,846,666 
It was believed that the 
Bila 45° 29,668,000 | 39,557,333 | \ returns respecting these 
DN Ae 36° 28,212,000 | 37,616,000] ( engines must have been 
inaccurate. 
5 Double... 42> 18,193,000 | 24,257,333 
6 Single... 63° 15,290,000 | 20,253,333 
7 Double... 45: 15,180.000 | 20,240,000 
8 Single... 45: 15,571,000 | 20,761,333 ‘ 
9 fe ele saa ae « 15,090,000| 20,120,000 | (02 the same mine. 
Tc ae eho be 14,384,000| 19,178,666 
11 Double... 42- 18,740,000 | 24,986,666 
12 Sinelemae 42: 15,532,000 | 20,719,333 
13) eee |) 236: 18,465,000 | 24,620,000 ‘ 
14 pee |e = | 12,228,000/ 16,300,588) 7 ae aay eee eee 
UE Seuss y tereyie 30° 14,050,000 | 18,783,333 
Ghanian, Cee can 20: 12,366,000 | 16,488,000 
17 Double... 14°75 6,097,000) 8,129,333 
18 Single... 30- 13,931,000 | 18,574.666 
19 sat ieiaers a 19,739,000 | 26,318,666 
D(Niwomeen ap ce, 6- 24,514,000 | 32,685,333 
ONE Reread Lact cease 21- 13,215,000 | 17,620,000 
DOr Oates 20: 15,034,000 | 20,045,333 
23/4, ..--| #8 _|/27,503,000|36,670,606| (PE 9 ae alae 
17,671,000 | 23,561,333 |General average in 1798. 
GitBert, Jbid, pp. 125-126. 
‘Tn 1798 an engine at Herland—found to be the best in the county,— 
was doing 27 millions.” 
Taytor, Records of Mining, i., p. 154; Quarterly Mining Review, ii., p. 
39; Annales des Mines, 3me. Série, ii., p. 56 
+ Gregory, Mechanics, ii., pp. 381-386. Farey, Steam-Engine, p. 389. 
Gilbert, Phil: Trans: exx., p. 125. Taylor, Records of Mining, i., p. 154. 
Arago, Life of James Watt, p. 56. Pole, Cornish Pumping Engine, pp. 36-40. 
Smiles, Lives of Boulton and Watt, pp. 234, 239, 257, 259, 278-281, 296-298, 
303-304, 320, 419-420. 
