340 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



A 21ft. diameter Waddle fan, with a trumpet mouth, is- 

 used for ventilation purposes. It revolves 28 to 30 times per 

 minute when the mine is idle, and 36 to 38 times when men 

 are working. It is provided with a Harding patent indicator to 

 record the number of revolutions the fan makes. The fan 

 only has one bearing, and that on the outside, so there is no 

 occasion for anyone to go into the air drift for oiling purposes, 

 and the air has free access to the fan. 



There are also six Buffalo fans driven by electricity used 

 to help on the air current in places. These are mounted on 

 trollies for convenience, in moving about. 



1'ig. 212. Avery Self -Indicating Colliery Weighing Machine. 



The skips are weighed 011 Avery machines, having a capa- 

 city of 2 tons, and capable of weighing 1000 tons each per day. 

 The platform, which is 4ft. by 3ft. 6in., has the usual system 

 of levers placed beneath it. This machine is so designed as to 

 be automatic and self-indicating, so there is no necessity for 

 the weighman to handle weights, poises or levers, when once 

 the machine is set. There is a steelyard with two gradua- 

 ted bars (Fig. 212), one a weigh bar graduated to 35 cwts. in 

 1 cwt. divisions, the other a tare bar marked by 71b. divisions 

 up to 10 cwt. There is also a quadrant, which has a range 



