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LI I. Intelligence and Miscellaneous Articles. 



DUTY OF STEAM-ENGINES. 



A REMARKABLE improvement in the duty of steam-engines 

 has of late taken place in two instances on mines in Cornwall, 

 which appears from the printed accounts which record the work 

 performed monthly by the engines at all the principal concerns. 

 Hitherto the best have reached only to 40 millions of pounds of 

 water lifted one foot high by each bushel of coal consumed ; some 

 have indeed occasionally done more, but not to any extent or con- 

 tinuance. 



The improvement which we now notice is in two engines erected 

 by Capt. Samuel Grose, and the only ones as we believe which he 

 has yet constructed. We are not acquainted with the exact nature 

 of the difference between these and other engines usually employed ; 

 but we believe there is nothing altered of importance in the general 

 principle, but rather in smaller details in matters which have been 

 hitherto overlooked. 



Whatever it may be, however, it is not less creditable to the en- 

 gineer, and is particularly worthy of praise, as not having been 

 attended, as we are told, with additional complication or expense. 



The first engine in which this improvement appeared was one 

 erected atWheal Hope, of 60-inch cylinder, working single as usual. 



The duty reported, is in April 42,101,739 lbs. 



May 42,?4I,650 



June 54,725,716 



July 55,012,292 



August 50,979,084 



These results are, however, much exceeded by the engine after- 

 wards built by Capt. Grose, at Wheal Towan, of 80-inch cylinder, 

 where the duty done has been 



April 61,877,545 



May 60,632,179 



June 61,762,210 



July 62,220,820 



August 61,764,166 



Thus exceeding by nearly 50 per cent what had hitherto been at- 

 tained. — We should be very glad to be able to lay before our readers 

 some good account of the particulars of this great improvement, 

 which we hear is in progress of being applied to other large en- 

 gines in the same district. 



ON THE USE OF CHLORINE IN DESTROYING FIRE-DAMP. 



To the Editors of the Philosophical Magazine and Annals. 

 Gentlemen, West Bromwich, Sept. 20, 1827. 



In your Number for August, (which I have only received within 

 a few days,) I observe a notice of a paper (communicated by Mr. 



Children) 



