TRAKSACTIOKS OF SECTION J. 463 



hills rising from it ; otherwise the line would run to earth at a 

 point which would necessitate a tunnel of abnormal length 

 and cost, such as to render the construction financially im- 

 possible. 



The disadvantage of locating a line on the hillside instead of 

 on the river-flats is obvious, as in one case spurs often break up 

 the line of the hill, which have to be curved roui:id, cut, or tun- 

 nelled through ; tributary streams fork out as they traverse the 

 hill-slopes, necessitating more numerous culverts or bridges ; 

 and the larger tributary streams often cut deep ravines in the 

 hillsides, which must be crossed by means of long, high, and 

 costly viaducts, or by high earch emba-nkments over expensive 

 culverts. Further difficulties may be met with in the form of 

 loose unstable ground, such as is seen on the mountain-sides 

 in New Zealand, forming the well known " shingle-slides," 

 which may have to be crossed by bridging, or, better, tunnelled 

 under in the sound ground behind. 



The line on the hillside, from the nature of its position, is 

 liable to heavy slips of rock or other material loosening from the 

 hillside above. These slips may carry away important works, 

 or block the line, and entail heavy charges for maintenance 

 and loss from stoppage of traffic. The line constructed on the 

 river-flats is free from many of these dangers, and experience 

 shows that the cost of construction is, together with the charges 

 for maintenance, much less in proportion. 



Such important differences affecting the financial prospects 

 of a mountain railway have met with due consideration, and 

 have led to the introduction of steep inclines worked with 

 special auxiliary power, the location of the pm'ely adhesion 

 line being in this case on the low sound ground as long as pos- 

 sible, thus concentrating the difficulties of construction and 

 haulage into certain sections, which can be treated specially. 

 This system of location is becoming more generally accepted 

 as the rational method in which to construct railways passing 

 through and over a mountainous district. 



One of the earliest and most successful examples of the use 

 of steep grades, with auxiliary powder, for surmounting ex- 

 ceptional heights, is the San Paulo railway in Brazil. In this 

 instance the steep grades a^re worked by means of a rope 

 actuated by fixed engines. The trucks are attached to the 

 rope, and are thus drawn over the steep-graded portion of the 

 line, and are afterwards hauled on their farther journey by the 

 ordinary adhesion locomotive engine. 



The San Paulo incline has a gradient of 1 in 9-75, and 

 mounts a height of 2,650ft. in five miles ; it has been in work 

 for twenty years without the loss of a single life ; during this 

 time 2,600,000 passengers and 4,000,000 tons of goods have 

 beeoi carried up and down the incline, giving a yearly average 



