Some Olservalions on Steam-Engines. 1 1 9 



From the foregoing Table it appears that the average duty of 

 the engines reported, exclusive of Wooli's patent engine, is at 

 this time about 20 millions. 



We have purposely kept out Woolf's patent engine*, because 

 one of the ends intended to be gained by tlie monthly report of 

 work actually done by the engines employed in the mines, par- 

 ticularlv in pumping, was to know the comparative merit of 

 Woolf's engine with two cylinders wben contrasted with the 

 steam-engines in common use. One of Mr. Woolf's engines 

 has been lately erected at Wheal Vor mine, of 53 inches diame- 

 ter in the great cylinder (the smaller cyhnder being about one- 

 fifth of the contents of tlie great one) and nine-feet stroke. Ac- 

 cording to Messrs. Leans' Report for May, the duty performed 

 by the engine alluded to, was 49,980,882 pounds hfted one foot 

 with every bushel of coals consumed ; and by letter we are in- 

 formed (for the printed Report lias not yet reached us) that the 

 duty performed by Woolf 's engine in the month of June was 

 50,333,000. 



Thus it appears that the average duty of the Patent Engine 

 for the months of May and June was jif/y milliovs, while the 

 aggregate average duty of the other engines is only twenty mil- 

 lions. From this it is evident that Mr. Woo'f 's improvements 

 on the steam-engine will be productive of much benefit to the 

 mining interests of the kingdom. On some of the large mines 

 when this engine shall have come into general use, wliich it must 

 do sooner or later, the saving in fuel only, will add to tlie yearly 

 dividends among the proprietors, several thousand pounds ster- 

 ling. Nor is this all : the expense that will thus be saved will 

 prevent numbers of mines from stopping work ; and will be the 

 means of setting many again to work which have ceased on ac- 

 count of the expense necessary to keep them free from water. 



Those of our readers who are not acquainted with the magni- 

 tude of some of the mining concerns in this kingdom, can form 

 no adequate opinion of the importance of such a saving in the 

 article of fuel, as is effected by Woolf's engine. They mav, 

 however, form some idea of it, when informed that the expense 

 of one of the large mines for coals only, to work their engines, 

 and keep the mine free from water, is about twenty-five thousand 

 pounds a year ! 



The improvement by which this great saving is effected, is not 

 the only one that Mr. Woolf has made upon the steam-engine. 

 He has, since the date of that patent, applied for and obtained 

 a patent for another improvement, by which he expects to be 

 able to effect a still greater reduction in the quantity of fuel re- 



* For a description of Woolf's Steam Engine, see vol. xix. p. 183; vol. 

 xxiii. p. 123 and 335; and vol, xlvi p. 43. 



H 4 quired 



