THE ACTING ENGINEER-IN-CHIEE.

11

D.—No. 5.

Wellington to Seventy Mile Bush, thence to Napier. 1. The survey of this line has been completed as far as Masterton in the Wairarapa, but the plans and estimates have not yet been received. 2. Between Masterton and the Manawatu Gorge a line has also been carefully explored, cut, and surveyed through the forest, which will answer in the first place as the basis for the line of road, and will ultimately serve for the railway line. The country generally is of a favourable character, and but one summit of any importance will be crossed, at an elevation probably of not more than 150 feet above the country immediately adjacent, and about 250 above sea level. The length of this section is about sixty-five miles. 3. From the Manawatu Gorge northwards to Napier the line through the bush, forty-two miles, already described as that on which a road was being felled and cleared, will also answer, with a few modifications, as the railway line; the country in the bush, as well as that beyond to Napier, being generally of a level character and favourable to railway construction. The plans and estimates of this latter section have not yet been received. In the first of the three sections above described, the prominent difficulty will be the crossing of the lliniutaka Kange. An easy solution of this difficulty appeared to be by piercing the hill with a tunnel; but an examination of the country which a tunnel line would necessarily traverse, led me to think that the problem would be more easily solved by crossing the range on the surface by a contour line, than by piercing the hill. The approaches to the tunnel would not be favourably situated, the country being very rough and irregular; while it was obvious that, to secure a line with a workable gradient, the level of the tunnel should be kept low, which would, of course, add to its length and costliness. These considerations led to instructions being given to prosecute the exploration and survey of a contour line, which was intrusted to John Rochfort, Esq.; the information then in our possession leading to the belief that a line having a gradient varying from 1 in 40 to 1 in 50 might be secured. The survey justified these expectations; as, after some exploration, a saddle was found some 400 feet lower than the one over which the road passes, and a trial line cut down each side of the range, with gradients corresponding with those mentioned. The ground generally is of a more favourable character than that seen from the coach road; but the hill sides, as usual in New Zealand ranges, are cut up with a number of gullies, and rendered still more irregular by several narrow projecting spurs. In many places these will necessitate the use of curves of not more than 3 chains radius, and in consequence the use also of engines fitted with special adaptations for passing round them. It is, however, practicable to work a line with such curves and on such a gradient, by adapting to it engines constructed for that particular kind of work. On the subject of the tunnel, an ad interim report from Mr. Rochfort has already been received, but at the time it was made we had not sufficient information to make a fair comparative statement of the advantages of either line. Another report, on fuller information, ■will be prepared and laid before you, in order that a just comparison maybe made as to the value of the two routes, and in order that the really best line may be chosen. The other portions of this section of the line require no special description. The Hutt Valley, from its peculiar character and its great liability to frequent and heavy floods, will demand very careful consideration in the laying off and actual execution of the works. The site selected for crossing the Hutt, that is, close under the hills, and about seven miles above the present bridge, is one not liable to change, and a bridge may there be erected with perfect confidence as to its permanence. The few miles between Pipitea Point, where the survey commences, and Petoni, or the entrance to the Hutt Valley, will require to be constructed entirely outside of the present road, and nearly on a level with it. In some places only will it be necessary to build a sea-wall, to protect the works from the action of the water in the harbour. The material of which the filling will consist will be of a stony or rocky character, obtained from different spurs along the road, and the slopes may be formed of the larger fragments, so as to be perfectly safe and permanent.

From New Plymouth to Wanganui, and thence to the Wellington and Napier line. Only portions of this survey have been executed, and none of the plans have yet been received. This line will form a junction with the Wellington and Napier line by way of the Manawatu Gorge, through which, as has been before explained, a line has been explored and surveyed for that purpose by Messrs. Stewart and Weber. The country from the Manawatu Gorge towards Wanganui and New Plymouth may be described as generally of a level character, but broken through at intervals by gullies and river beds of every imaginable form, depth, and character. There will be many long stretches of almost level land, over which a railway line may be constructed at a very moderate cost; but the numerous bridges and viaducts that will be required, some of them of a costly character, will bring up the average cost per mile very considerably, and possibly quite as high as any of the amounts authorized in the Schedules of the Public Works Act, viz., £5,000 per mile. I state this without having any plans or sections as a guide, but from a personal inspection of the country and of its general character.