626 PROCEEDINGS OF SECTION J, 



The smaller creeks and watercourses are carried either under 

 the canal by brick syphon culverts or over it by wrought-iron or 

 timber flumes. At a little beyond the tenth mile the water passes 

 into Devine's Tunnels, six hunch'ed feet and two thousand six 

 hundred and eighty feet in length respectively, driven through the 

 sandstone rock, and being of the same dimensions and gradient as 

 the Cataract Tunnel. This is the last of the unlined tunnels, all 

 other tunnels below this are in shale formation and are bricked 

 throughout with thi^ee rings, in exceptionally bad places with four 

 rings. At a little over fourteen and a-half miles the water dis- 

 charges into the Sugarloaf Tunnel, 3907.52 feet in length, nine 

 and a-half feet wide and seven and a-half feet high, the gradient 

 being six feet per mile. 



The canal up to this point has a gradient of twenty-one inches 

 per mile and is twelve and a-half feet in width with vertical sides, 

 except in a few places, for instance between Woodhouse's and 

 Menangle Creek, where the ground was bad, with a steep cross 

 slope, the walls were battered and otherwise made stronger. 



At about three hundred and fifty feet beyond the outlet of the 

 Sugarloaf Tunnel, there is a vertical drop in the canal of eight 

 feet. Here there are sluice gates by shutting which the entire 

 supply can be stopped if required or in case of accident. The 

 water in such a case would pass over a large waste weir, and dis- 

 charge into a natural watercourse leading to the Nepean about a 

 mile distant. 



After leaving the drop the gradient of the canal changes to two 

 feet per mile with a width of twelve feet and a depth of eight feet. 

 At about sixteen and three-quarter miles the section of the canal 

 changes to one with sloping sides, the depth of water being seven 

 feet, and width nineteen feet at that level, the gradient remains 

 the same over this portion, viz., two feet per mile. 



The Great Southern Railway is crossed at seventeen miles by 

 means of a wrought-iron pipe on brick piers eight feet diameter, 

 with spans two of eleven feet, one of fifty-one feet, one fifty-two 

 feet, and one sixty feet, making the total length one hundred and 

 eighty-five feet. The height above rail level is thirty -five feet, and 

 the gradient 1 in 215.87. Over the sloping ground on each side 

 of the railway, the canal is carried in embankment, the sides and 

 invert being concreted. 



At seventeen and a-half miles there is a substantial brick 

 aqueduct over a deep depression, called the Kean's Creek aqueduct 

 and four hundred feet beyond this the water enters the Mount 

 Anna Tunnels, 2,248 feet and 366.6 feet in length separated by 

 a piece of covered way two hundred and thirty-seven feet long. 

 The smaller tunnel is curved on plan and both are similar in grade 

 and cross section to the Sugarloaf ; the covered way has a gradient 

 of four feet per mile. The canal with sloping sides and gradient 



