PRESIDENTIAL ADDKESS. 1 7 



1 in 40 grade falling from Sydney, and remained an obstruc- 

 tion to the South Coast traffic until recent years. With 

 the application of mechanical ventilation, consisting of a 

 sirocco fan developing 170 H.P., and supplying air at the 

 rate of 250,000 cubic feet per minute, a beneficial change 

 has been effected, not only to the travelling public and the 

 enginemen, but owing to the rails being kept dry by the 

 air in motion, there is a noticeable increase in the load 

 hauled. The work of cutting out the Otford Tunnel by a 

 deviation between Otford Station and Coal Cliff is now well 

 in hand, and when complete, great relief will be experienced 

 by all concerned. 



The main difficulty on the Main Western line was the 

 descent into the Lithgow Valley which was negotiated by 

 the great Zig Zag, a fine work in its day, but not suitable 

 for the heavy traffic of later years. It became apparent 

 that some better means must be provided, and many trial 

 surveys were made, the result being that a scheme was 

 prepared by the Engineer-in-Ohief, and approved by the 

 Commissioners. 



This work, which was commenced in 1908, and opened for 

 traffic on 16th October, 1910, calls for special reference, 

 not only because there were eleven tunnels to be driven, 

 but also, owing to the great urgency for completion, special 

 methods had to be adopted in dealing with the supply of 

 material, and providing arrangements such as would allow 

 of as many tunnels as possible being dealt with simultane- 

 ously. A difficulty with regard to the provision of the 

 material for tunnel lining, platelaying etc., presented itself 

 owing to the fact that the No. 1 and No. 11 tunnels— the 

 longest — were at almost the extremities of the work. At 

 the Sydney end, connection was possible with the main line 

 at Clarence, and a suitable depot was formed there to deal 

 with the material required at No. 1 tunnel end. A con- 



B— May 2, 1917. 



