153 REPORT — 1867. 



Findhom. This summit is 1046 feet above the sea-level. It afterwards de- 

 scends to Forres (the point of junction with the base-line) by gradients, the 

 steepest of which are 1 in 70 ibr S miles, and 1 in 70 for 4 miles. 



In this length of the main direct line of 104 miles, there are two small 

 tunnels, one of 350 yards near Dunkeld, and the other in the Pass of Killie- 

 crankie of 110 j-ards in length, both constructed very much with the view of 

 avoiding injury to the adjoining scenery. 



The principal difficulties that arose in laying out the line were in passing 

 through the narrow defile at Dunkeld, the beautiful demesne of the Duke of 

 Athole, and again in penetrating through the picturesque Pass of KiUiecrankie, 

 where the mountains, as it were, close in upon each other for a great height ; 

 likewise in passing along the narrow, precipitous, and rocky valley of 

 the Garry, close to a large and rapid mountain-stream ; also the Park at 

 Castle Grant, and the defile at Huntley's Cave near Grantown. These 

 points in particular required much study, with repeated trial and contour 

 levels, so as to obtain a kno-wledge of the precise formation of the ground, 

 and to choose the best direction at the lowest possible cost. At the Pass of 

 KiUiecrankie the banks were so precipitous and steep that the line had to be 

 supported by breast or retaining walls to the extent of 690 lineal yards, and 

 to the average height of 26 feet, the extreme height of one being 55 feet ; 

 and in order to carry the railway at the narrowest point in the Pass where 

 the precipices close in, as it were, on either side, and afford scarcely any ad- 

 ditional space beyond that occupied by the channel of the river, instead of 

 supporting the line by brcastwaUs, it was deemed prudent to construct a 

 viaduct of 10 arches, 60 feet above the river, which with a tunnel at the 

 north end carries it successively through the Pass. At two other points on 

 the line, in running up the sides of the Garry, brcastwaUs had to be formed, 

 respectively 94 and 35 yards in length, and 15 feet in average height. All 

 these breastwalls, extending to 1650 lineal yards, are buUt with Ume, and 

 set on a solid foundation of dry gravel or rock, at right angles to the face of 

 the waU, which batters at the rate of 1| inch to the foot. 



The spaces behind the waUs are fiUed with rubble stones, set by hand for 

 10 feet wide, and further back with dry gravel, it being important that aU 

 earth or clayey substances should be excluded. The writer prefers the curved 

 to the straight batter, as it gives more effectual resistance if well built ; but 

 breastwalls are to be avoided wherever earth embankments can be substi- 

 tuted, as, in his experience, there are subtle influences in the Scottish climate 

 of alternate frost and wet in winter, which operate imperceptibly to their 

 destruction, and they require careful and constant inspection. Except where 

 those breastwaUs became necessary, the whole of the lines were formed in 

 cuttings and embankments, and for considerable distances along the slopes of 

 vaUeys. Where the ground was precipitous or irregular in the cross 

 section, level benchings were formed, 10 feet in width, immediately under- 

 neath the pei-manent way, in order that the sleepers should have an equal 

 and solid bearing throughout. 



In rimning through so large an extent of mountainous country, the line, 

 as might be expected, had to pass over some lengths of soft ground and 

 morass. The piincipal of these were for two mUes near the town of Nairn, 

 also for about two miles near Keith, one mile on Dava Moor, and about a 

 mile in crossing through a hoUow at Drumochter on the summit of the 

 Grampians. In aU places where the ground was particularly soft, a uniform 

 mode of treatment was adopted. Two par;iUel drains were first cut outside 

 the fences, about 50 feet apart, from 4 to 6 feet deep, and with slopes of 1 



