OSBORXE-WALLSEND COLLIERY. 221 



single cylinder horizontal engines arranged end on, but only 

 one is used at a time, the other being held in reserve in case of 

 necessity. The air is split in the air drift so that it can be 

 drawn through the fan from both sides. The top of the air 

 drift is made of galvanised iron, which is purposely made 

 the weakest part, so that in case of an explosion, this will give 

 way and can be readily repaired, instead of the fan becoming 

 destroyed. When, men are at work, the fan makes forty revolu- 

 tions per minute, using a pressure of one and one-tenth inch 

 water gauge ; but when the mine is idle, it is only given twenty 

 revolutions. 



There are two water rings in the shaft made by 

 building in ordinary wooden curbs, above which the brickwork 

 is shorn back; on to the front of the curb is fastened a rim of 

 sheet iron to retain the water which is eventually led down the 

 side of the shaft in a pipe. There is a single cage in the air 

 shaft that runs on rope guides, the hoisting being done by a 

 geared duplex engine, which drives the single drum. Electric 

 signals and telephones are used throughout the mine. 



The seam being worked averages Tft. Gin. in thickness, but 

 in places it is subject to rolls where the floor rises up; the 

 roof is seldom affected. The tops of the rolls are invariably^ 

 accompanied by so-called grey heads, which are joints, run- 

 ning in the same direction as the longer axis of the roll, 

 coated with a whitish substance. By the trend of these grey 

 heads, the miners can tell how the rolls are running. They 

 are also known as "leaners," as their faces incline towards 

 the axis of a roll. 



The coal is worked by the ordinary bord and pillar 

 method. The bords are started with a four yard neck, and 

 are then widened out on either side to eight yards. If the 

 coal will not stand well, the pillars are worked out quickly. 

 When winning pillars, the coal is extracted in eight yard lifts. 

 A series of pillars are worked out at an angle so as to leave 

 strong ground behind the men for escape in case of necessity. 

 The holing is all done by pick, and the coal is shovel-filled. 

 When the coal has to be blasted down, monobel is used as the 

 explosive. Old double-headed rails resting in chairs set in the 

 rock serve as collars in the return air-ways, where wood might 

 rot with damp and fungi. 



Formerly the main and tail rope system of haulage was 

 employed underground, but this has now given place to the 

 endless rope system. The effect of the great strain on the old 

 drums, due partly to ihe rope which is wound on hot during 

 the day and remains coiled up during the night, when it 

 cools and contracts, can be seen bir the way it has had to be- 



