196 Description of a Machine for- raisi7}g Coals 



which work vertically to move in, and keep the coils at an 

 equal distance from each other. 



The wrought iron lire is of two kinds, the one for coni- 

 cal, and the other for cylindrical barrels ; the cross section 

 of that for the barrel formed of frustums of cone<, is nearlv 

 a parallelogram, 1^ inch by l-ths, out of the upper part of 

 which about one-fourth of an ellipsis is taken, to form a 

 horizontal bearing for those links of the chain which lie flat 

 upon the tire ; the cross section of the latter is a rectangle 

 li inch by -i- inch. Both are rolled into their proper form, 

 and holes of a quarter of an inch diameter punched therein, 

 at a foot from each other, for the purpose of nailing them 

 to the planking of the barrels. 



As the method of working chains in grooves has only 

 been in use about three years and a half, it is impossible to 

 give a certain idea in respect to their durabilitv. In all that 

 time not a single link has broke, or the least accident oc- 

 curred therefrom, though Messrs. T. W. and B. Botfield 

 have nearly three thousand feet in daily motion at this ma- 

 nufaptory. The wear has also been so trifling, that I con- 

 ceive they will sooner fail from oxydation than attrition : 

 for although 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 seldom disturbed by the motion of the chain. 



The method of folding wooden barrels with wrought iron 

 tire, does away the necessity of cast iron ones, and may be 

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

 as may be seen by the estimate which is subjoined. 



There are now at work in the mines of this manufiictory, 

 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 

 of chains for hempen ropes at all our mines and manufac- 

 tories, a matter of importance to the British empire, as it 



will 



