134 COALFIELDS AND COLLIKIUES OF AUSTRALIA. 



For some of the following 1 figures I am indebted to a paper 

 on "The Deep Sinking of Shafts at Sydney Harbour Colliery," 

 read by Mr. J. L. C. Rae before the Engineering Association 

 of N.S.W. on 15th October, 1900. A temporary sinking en- 

 gine was erected at each of the shafts, which is placed so close 

 to the shaft that there is room behind for the permanent en- 

 gine to be erected. The Birthday shaft engine consists of 

 a pair of horizontal, coupled, direct-acting, high-pressure 

 winding engines with 28in. diameter cylinders, and 5ft. 

 stroke. It is provided with Cornish equilibrium valve gear. 



Fig. 70. Cornish Valve. 



link motion reversing gear, steam valves Sin. in diameter, 

 exhaust valves 9in. in diameter, and Cornish equilibrium throt- 

 tle valve. There is only one winding drum, which is 14ft. in 

 diameter, by 5ft. Gin. wide, with a splash board to prevent the 

 dressing from being thrown off the rope about the engine 

 room; it is provided with two brake flanges, one on either 

 side; these were originally rough, and fitted with wooden 

 blocks, on which a wrought iron brake strap, operated by the 

 enginedriver's foot, worked half-way round the circumference. 

 This was subsequently altered, the flanges being turned while 

 in their present position, and fitted with brake blocks on long 

 levers of the Burns type, and the leverage increased, it now be- 

 ing 64 to 1. An auxiliary drum was keyed on to the crank 

 shafting inside the main drum while sinking, on which that 

 part of the sinking rope not actually in use for the time being 

 was coiled. As sinking proceeded, this rope was paid out by 



