MACHINE FOR RAISING COALS OR OR,E, |25 



tory. The wear has also been so trifling, that I conceive 

 they will sooner fail from oxidation than attrition: for al- 

 though the machines for raising coal and ore from the mines 

 are in use twelve hours in the day, the brown oxide of iron 

 formed upon the links by exposure to the atmosphere is sel- 

 dom disturbed by the motion of the chain. 



The method of folding wooden barrels with wrouglit iron Cast iron bar- 

 tire does away tiie necessity of cast iron ones, and may be ^^^^ unneces- 

 applied to every wooden barrel now in use at a small expense, 

 as may be seen by the estimate which is subjoined. 



There are now at work in the mines of this manufactory 

 four machines, with wooden barrels folded with wrought 

 iron tire, one cylindrical, and three formed of frustums of 

 cones, raising upwards of eight hundred tons of coal and 

 iron ore per week from pits of about eighty yards deep; and 

 three others are in hand. 



I look forward with confidence to the general substitution Chains used 

 of chains for hempen ropes at all our mines and manufac- in'^'ead of 

 , . X- r ■ X i. xu Tj -i.- 1 • . hempen ropes, 



tones, a matter or importance to the Jiritish empire, as it 



will considerably lessen the consumption of hemp, and ren- 

 der it more abundant for the exigencies of the Navy. 



Wishing to give this method of working chains all the 

 publicity in my power, I will obviate all apparent (for there 

 are no real) difficulties, which may occur to any person in 

 their application, on his stating them in a letter post paid 

 addressed to me here, 



I am, Sir, 



Your most obedient Servant, 



GILBERT GILPIN. 



Expense of tarred ropes for a machine for raising coal and Comparative 

 ore from a pit eighty yards deep, for three years and four ^g™^^^ ''* 

 months. 



£ s. d. 



Ten ropes each 110 yards long, 6 inches in cir- 

 cumference, and 5lbs. per yard, 5500lbs. at 

 8c/. per lb 183 6 8 



Deduct 10 worn out ropes 2750lbs. at id. lb •• 11 9 2 



Net expense of ropes for 3 years and 4 months ^171 17 6 

 1 2 Expens« 



