314 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



gauge pressure, but capable of going 60 revolutions per 

 minute. The driving engine was manufactured by the Wad- 

 dle Patent Fan and Engineering Company, of Llanelly, 

 Wales, and is a compound tandem, direct acting. The emer- 

 gency engine, which is placed in line with the main engine, 

 but on the other side of the fan, only has one cylinder. As 

 the fan must revolve in the same direction all the time, when 

 the emergency engine is coupled up to it, the connecting rod 

 works under and over, instead of over and under. The result 

 is that the upper guide bars become hot, owing to the greater 

 friction of the guide blocks attached to the crossheads when 

 worked that way. Waddle's fan is known as an open running 



Fig. 201. Lamp Cabin. 



fan; that is, it is open to the atmosphere all round the cir- 

 cumference. The blades and casing all revolving together. 

 The air is taken into the fan on one side only, and on that side 

 the casing is widened out. The blades, which are inclined 

 backwards, are alternately long and short. The long blades 

 reach the centre, and so as to give the maximum area for the 

 entrance of the air, they are increased in width as they near 

 the centre. On account of the large diameter, a hi^h 

 perpheral speed is obtained with a comparatively small num- 

 ber of revolutions. As seen in Fig. 200, the fan is narrow, 



