84 C O. BURGE. 



NOTES ON RACK RAILWAYS. 



By C. 0. BURGE, M. Inst. C.E. 



[Read before the Royal Society of N. S. Wales, August 8, 1900, ,] 



The method of overcoming the difficulties in railway construction 

 caused by unavoidable steep ascents, by means of the rack and 

 pinion connexion between locomotive and road, is a comparatively 

 old one, but it has only been in quite recent years that it has 

 been carried out to any great extent. As there are now nearly 

 one hundred rack railways in various parts of the world in use, of 

 which some are in the neighbouring colonies, and as surveys have 

 been made and information obtained by the Railway Construction 

 Branch, N. S. Wales Government, with the view to their intro- 

 duction here, it was thought that a few notes on the subject might 

 be acceptable to the Society. 



Ordinary road traction is heavy owing to two causes, friction 

 and unevenness. Friction, because the wheel under its load sinks 

 in the ground and friction is set up between the sides of the rim 

 and those of the groove made by the impression of the wheel ; and 

 unevenness, because the ground, not being of uniform hardness, is 

 shaped at the bottom of the groove, by the load, into a succession 

 of small grades, which have to be overcome. To avoid these, iron 

 plates, a century ago, were laid upon the road, thus forming the 

 rudimentary railway from which all the enormous subsequent 

 development has sprung. The name of this primitive contrivance 

 for ordinary horse traffic, survives in that of the "plate-layer" of 

 the modern railway. Edge rails, as they were called, and the 

 steam locomotive followed ; but the introduction of the smooth 

 and hard rail brought with it difficulties of its own in respect of 

 what .is known as adhesion — difficulties which were practically 

 imperceptible in the ordinary road. 



