COURIMAL-BALGOWN1E COLLIERIES. 



211 



The advantages of the endless rope system over the usual 

 open rope system employed with the gravity planes on the 

 South Coast, is that the weight of the rope on the up hill side 

 is al \vays neutralized by tlie weight of the rope on the down 

 hill side ; with the endless rope it does not matter if the track 

 undulates, so long as the general fall is sufficient; with long 

 inclines it is not necessary to have such a steep grade when 

 employing an endless rope, as with an open rope ; also the con 

 veyance of coal is more uniform. 



I 



Fig. 133. 



The empty skips weigh about 6cwt., and can hold 18cwt. 

 of coal; the maximum number of skips on the incline at a 

 time is 22 on each track, or a total weight of 26 tons 8cwt. 

 of full trucks, and 6 tons 12cwt. of empties. 



Pooley's weighing machines are now used for weighing 

 the skips of coal. 



A platform weighing machine should work equally well 

 irrespective of the position of the load on the platform. Care 



Fig. 134. Platform Weighing Machine. Plan View. 



should be taken that the machine is level. These machines 

 are constructed on the Beranger principle. The platform 

 rests with one end over a lever as at (A) (Fig. 133), and the 

 other end on a second lever as at (a). These levers must 

 be similar, that is, the ratio of the arms (FA) to (FB) and 

 (fa) to (fb). If this ratio be 20 to 1, then every ton on the 



