490 Mr. Henwood on the Cornish Pmnjnng-Efigities. 

 The results will appear in 



Table V. 



III. — The "iSsork accomplished for a certain expense. — The 

 foregoing details supply all that is requisite for this inquiry, 

 except the prices of the materials consumed ; these were coal, 

 at the rate of forty-one shiUings for 72 measured bushels f; 

 grease, forty-five shillings and sixpence per 11 '2 lbs. ; and oil, 

 four shillings and twopence per gallon; at which rates the 

 results were by Huel Towan, Wilson's engine, 1085 tons; 

 Binner Downs, Swan's engine, 1006 tons; East Crinnis, 

 Hudson's engine, 870 tons; lifted one foot high for the ex- 

 pense of one farthing. 



As supplementary to the general object of the first part of 

 this inquiry, it may be useful to compare the ma.xima of press- 

 ures which obtain in the cylinders, with known elasticities in 

 the boilers ; the loads of the engines remaining unchanged. 



Table VI. — Load of engines, and relative pressures of steam 

 in the boilers a7id cylinders. 



Mines and Engines. 



Huel Towan, Wilson'sJ 

 Binner Downs, Swan's 

 Bum's 



East Crinnis, Hudson's 



Huel Vor, Trelawny's 

 , Borlase's 



Load on the 



Piston, in lbs. 



per square 



inch of 



its area. 



10-2 



10-23 



10-7 



11-4 



14-7 

 121 



Pressure of steam in lbs. per 

 square inch. 



In the Cylin. 

 In the Boiler. der%. 



61-8 

 ■ 74-78 



58 

 "55 

 [36-8 

 '26-3 

 ■47 



40 



27 



26 



25 



30-5 



25 



21 



30-5 



30-5 



• These numbers are on the assumption that each pump delivers the 

 full computed quantity : but in an experiment at Huel Towan, made by 

 Sir John Rennie and myself, the actual compared with the calculated deli- 

 very was as 0-924 to unity. I have repeated the comparison at the same 

 place, with a similar result. 



t The bushel measure with a heaped licad is the same wiiich was used 

 in Mr. Watt's time, varying only as jjrescribed by law. 



X The figure in p. 482 refers to this engine. 



§ All the pressures mentioned throughout this paper are absolute, and 

 as if acting against a vacuum. 



