TEANSACTIONS OF SECTION J. 465 



Take, for argument, 13-02d. as the engine-cost per train-mile on 

 the l-in-60 (and it must be remembered that 13-02d. is given 

 as the average cost throughout the five chief sections of rail- 

 way in New Zealand, and no doubt the average grade would be 

 much below this — probably under 1 in 120) : to reduce the cost 

 of working the Fell engine per train-mile to the average cost of 

 the ordinary engines per train-mile on the five chief sections, 

 on the assumption that they work throughout on an average 

 of l-in-60 grade, 44-14d., the engine-cost per train-mile of the 

 Fell engines, must be divided by 4, which equals ll'035d. per 

 train-mile, as against 13-02d., the average cost per train-mile as 

 before stated. 



Eeducing the problem of along easy-grade line versus short 

 steep grades and low-grade approaches down to first principles, 

 it will be remembered that the mechanical energy which must 

 be expended in raising a weight through a given height is equal 

 in amount if the w^eight is raised by means of a long inclined 

 plane, or lifted directly through the given vertical height equal 

 to that reached by the inclined plane. This fact eliminates any 

 question of total energy expended in the two systems, beyond 

 that of increased friction due to distance, which is in favour of 

 steep inclines, and reduces the question to one of efficient ap- 

 plication of working details and the cost of construction and 

 maintenance, by the two methods of locating and working a 

 mountain railway. 



Since the introductioii of the Fell systena, which has the 

 defect of being, like the ordinary locomotive, dependent en- 

 tirely on adhesion for its haulage-power, and therefore suffers 

 in efficiency from climatic changes, there has been a great 

 stride made in working steep-grade inclines. These improve- 

 ments are embodied in the Abt system, of central rack, and 

 rack-engine. This motive-power has long passed the period of 

 doubt or theory, having stood the test of some years' practical 

 working. This special method of traction for inclines is the 

 invention of Mr. Eoman Abt, of Switzerland. 



Briefly, the leading features of the system are, the form of 

 rack-rail, which is fixed between the ordinary carrying-rails, 

 and is built up of a number of individual elementary racks 

 placed side by side. Each one of these is of the siuiplest form, 

 being a bar of steel with teeth cut in one edge. Each rack 

 can bear safely a certain strain, and the number is increased 

 in proportion to the duty required. 



These individual racks are laid so that the pitch of the 

 teeth is stepped, or what is technically termed " staggered," 

 the teeth of one bar being slightly in advance of the teeth of 

 the next, and so on. The teeth in the engine-pinion are made 

 to correspond to those in the rack-bars, and are also stepped, 

 producing a simultaneous contact of several teeth, which in- 

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