86 C. O. BURGE. 



two racks side by side, the teeth of which are staggered, that is to- 

 say the tooth of one is opposite the space of the other, an 

 additional engine pinion being set to correspond. On extremely 

 steep grades or where loading is heavy, three racks have been 

 used, where the teeth of each are set one-third of the pitch behind 

 its neighbour. Hence, should there be a failure in one set of rack 

 or pinion teeth, the other set serves to hold the engine. Moreover 

 there are generally two sets of pinions, set tandem fashion and 

 coupled, to each rack. 



The following is the description of the permanent way of the 

 Nilgiri rack railway, which is one of those most recently laid, and 

 is from the Government Report. I have had some particulars of 

 this line, which is 'on the metre gauge, courteously supplied by an 

 old colleague — the present Engineer-in-Chief, Madras Railway — 

 and the rack line in question is an extension of a branch line with 

 which I was connected when in India. 



The rails are 50 lbs. steel, flat footed, 28 ft. If in. long on the 

 straight, held down by single spiking, except at joints, where the 

 outer spikes are double. The rails are fastened with deep, angle 

 iron, six bolted, fish-plates, weighing 40 lbs. per pair. The sleepers 

 are of Pyngadu wood, spaced 2 ft. 6-jV in. apart, size 6 ft. x 8 in. 

 x 6 in. The rack is a double plate Abt steel rack on cast iron 

 chairs, weighing in all 90 lbs per yard. The length of the rack bars 

 is that of four sleeper spaces. The bars break joint, and are each 

 4tV in. x | in., the pitch is 4^i in. and the pitch line is -ff- in. below 

 top of bar. The two bars have a space of If in. between them. 

 The slope with the vertical of the rack tooth at pitch line, is 1 

 in 4. The radius of pitch circle of pinion is 11 \ in. full. There is 

 a pair of pinions keyed on to the rack shaft to correspond with the 

 pair of rack bars. The rack teeth break pitch. The foregoing 

 dimensions are mostly given in millimetres in the report, and are 

 converted in the above to the nearest equivalent in sixteenth parts 

 of an inch. The steepest grade is 1 in 12 J, and the sharpest 

 curve 328 ft. or about 5 chains, radius. 



