NORTH BULLI COLLIERY. 173 



distance for conveying' the coal, saves much original driving 

 oi narrow work. The longwall cutter is used in the bords 

 with success; it doing- better work than hand labour. 



The endless-rope system of haulage is employed under- 

 ground, driven by a semi-portable boiler and engine situated 

 outside the mouth of the intake tunnel. The intake and re- 

 turn tunnels are about 50 yards apart, and are connected every 

 80 or 90 yards by stentons. The roadways are 12ft. wide and 

 8ft. high. Horses 11 to 14 hands high gather the skips from 

 the working places. The skips hold about 15cwt. of coal; they 

 have to be built low on account of the low roof. Four full 

 skips or ten empties go to a set. They wait for a larger 

 number of empties, so as to save time when clipping on, and 

 also to save the wear of the rope where the clips fasten. 

 Lang's lay rope is used, it being found most suitable for 

 hauling purposes where drums and pulleys are comparatively 

 small, and where the ropes are subject to severe side friction. 



On arriving at daylight, the skips are weighed on art 

 Avery's self-registering weighing macliiue, capable of 

 weighing up to 30cwt. They are then run into a side tippler 

 with a counter weight below, so as to right itself again after 

 the coal has been discharged. The tippler is regulated by a 

 brake, so as not to smash up the coal when dumping on to 

 the screens. A side tippler has an advantage over an end 

 tippler inasmuch as an empty skip need not pass out the same 

 way as it entered, but can be pushed out the opposite end 

 by a full skip ; also a side tippler does not deposit the coal 

 in such a small heap as an end tippler. The screen is 

 stationary, but has a movable chute. The classes o? coal 

 produced are: 1st, Best screened, i.e., over }in. ; 2nd, un- 

 screened, with or without the duff taken out; 3rd, nuts be- 

 tween ^in. and Jin., and duff under -Jin. There is a self- 

 acting incline from the mine to the level of the railway : 

 the top portion has three rails, at the meeting there are four, 

 while the bottom length has two. 



The workshops are fitted with lathes, drilling machines 

 and other necessary plant. 



The ventilating current is produced bv a 10ft. diameter 

 Walker fan, into which the air passes from both sides. This fan 

 is given 150 revolutions per minute and delivers air with a pres- 

 sure of 1.3in. water. It is driven by a single cylinder engine pro- 

 vided with a Meyer's cut-off valve, by means of two manila 

 ropes. The driving pulley has five grooves, and is geared 3 to 

 1. Both fan and engine were made by William Davies, of Wol- 

 longong. Provision is made for adding another engine to the 

 other end of the crank disc, so that by turning the connecting 

 and eccentric rods round, they can be connected to the dupli- 

 cate engine when necessary to use it. The fan is situated 



