As a matter of fact, the extent of timber trestling upon this railway cannot fail to impress the visitor. In the valleys the line is laid almost entirely upon a wooden grade, owing to the absence of stable solid ground upon which to raise embankments, while the rivers are spanned by steel bridges ranging in span from 80 to 100 feet in the clear. As the rivers rise and fall considerably according to the season, the abutments had to be set well back from the low channel, and, moreover, had to be protected heavily by piling to withstand the severe scouring that takes place when the waterways are in flood and they rush along with the speed of a cataract. More than 50 per cent. of the work through the canyon is tunnelling, which aggregates 2,800 feet out of 4,800 feet. There was no other way of overcoming the abrupt cliff-sides, and but for the rifts and clefts in their flanks its extent would have been greater. This was the work which occupied so much time and consumed so much money, for the rock was found to be intensely hard. Steam drilling was attempted at first, but the temperature within the borings rose so high as to become intolerable. Therefore this plant had to be discarded in favour of compressed air drills. With their aid a hole 21 feet in height, by 14 and 16 feet in width, to carry a single track, was hewn and blasted out. The installation of the power plant to operate the drills was a pretty problem. It could not be set up on the same side of the canyon as the borings were being made, so had to be rigged up at a convenient point on the opposite wall near the upper end of the gorge, the power being transmitted through piping. In order to carry the latter across the gulch a temporary suspension bridge 130 feet long was erected, and as it was also employed for the purpose of conveying materials and men from one cliff to the other, was made heavier than otherwise. In addition to perforating the shoulders of the mountains, deep clefts in the mountain faces had to be spanned or masses of obstructing rock had to be blown out of the way. In one instance there was a couloir which required a 90-foot span bridge to cross from one side to the other, while in another case 300 feet of solid rock, aggregating over 50,000 tons of rock, had to be torn down to enable the grade to proceed from one tunnel to the other. About thirteen months were required to carry the line through this stretch of 4,800 feet.