BURWOOD EXTENDED. 319 



The Guibal fan is 35ft. in diameter and 10ft. wide; the 

 tips of the vanes curve slightly like a scoop. The fan the 

 casing of which can be seen in Fig. 205 runs at 33 revolu- 

 tions per minute, and supplies 99,000 cub. feet air per minute. 

 The fan engine was made by the Grange Iron Company Limi- 

 ted, of Durham, England, and is supplied with variable ex- 

 pansion. 



Fig. 205 Pithead Frame and Fan. 



The mine timber is classified according to their lengths, 

 and are stacked at the surface between posts on which are 

 marked their lengths, so there is no time wasted in sorting out 

 the length of prop desired when wanted for use. 



The Maitland Field. 



The Greta seam, which is the next largest producer of coal 

 to the Borehole seam in the Northern coalfield, was first lo- 

 cated in the Cessnock to Homeville part of the Maitland dis- 

 trict, near where the Abermain colliery surface works are now 

 situated, by a geological survey party under Prof. David, in 

 1886. Now, this is perhaps the most important of our coal- 

 fields, and contains the thickest known seam in New South 

 Wales, from 14ft. to 34ft. thick. This discovery resulted in a 

 large area of land being reserved in the interests of coal min- 



