Intelligence and Miscellaneous Articles. 3 i 3 



to 182C the steam cases of the cylinders were not clothed, but exposed 

 to the air. 



Years. 



Millions. 



Years. 



Millions. 



1816 



36.3 



1823 



42-1 



1817 



41-6 



1824 



43-5 



1818 



39-3 



1825 



45-4 



1819 



40-0 



1826 



45-2 



1820 



41-3 



1827 



59-7 



1821 



42-8 



1828 



77-3 



1822 



42-5 



1829 



76-2 



The advance made in 1827, and since that time, has been effected 

 by good management of the engines, chiefly by clothing all the steam 

 vessels, and thus preventing any needless waste of heat by radia- 

 tion, also by using better boilers *$ but the engines are strictly accord- 

 ing to Mr. Woolf's system of high-pressure steam acting expansively 

 in one cylinder. 



Great credit is due to Captain Samuel Grose, who began the race 

 of improvement in management ; first in an engine which he made at 

 Wheal Hope in 1825, and still more in another which he made the 

 next^year at Wheal Tovvan, with an eighty-inch cylinder ; in 1827 

 it averaged 58* 18 millions, its highest being 62*22 in July. 



At the end of 1827 Mr. Woolf removed the ninety-inch engine 

 before mentioned at Wheal Alfred (that mine having ceased work- 

 ing) to the Consolidated mines, and by good management and 

 clothing it raised 64*42 millions on the average of the last three 

 months, the highest being 67' 10 in November. 



In 1828 Captain Grose brought the annual average performance 

 of Wheal Towan engine to 77*29, the highest being 87*05 millions 

 in April f. Mr. Woolf's engine averaged 62*57, and its highest was 

 67*56 millions in May. These striking examples stimulated the ex- 

 ertions of all the Cornish engineers to take the same care in manage- 

 ment, and with such success that the average of all the engines in 

 1829 was 41*22 millions; although in 1814, before Mr/Woolf's 

 system was begun, it was only 20*37, or less than half. The number 

 of engines and the power exerted by them is more than doubled, 

 whilst the quantity of coals consumed by them is sensibly lessened. 



The importance of such an increase of power from the same fuel, 

 to the success of mining in Cornwall, may be estimated by the follow- 

 ing account of the Consolidated and United mines, which are worked 

 by one company of adventurers, and form the largest mining esta- 

 blishment in existence. 



The United mines are worked to a loss, and are only kept drained 



* See Mr. John Taylor's paper on these boilers, Phil. Mag. and Annals, 

 N.S. vol. i. p. 126,- they are long cylinders containing cylindrical tubes 

 within them, for the furnaces : on a plan which was first brought into use 

 for high-pressure steam by Mr. Trevethick in 1804. 



-f See Mr. John Taylor's account of the performance of this engine in May 

 1830, when on an accurate trial of about two hours and a half working, it 

 raised 92 33 millions. 



N. S. Vol. 8. No. 46. Oct. 1830. 2 S to 



