CONSTRUCTION OF RAILWAYS.

11

D.~Iv To. 8l

V.—TOKOMAIRIRO TO TUAPEKA. No. 5. Mr. AY. N. Blaie to Mr. J. Blackett. Sic,— Dunedin, 24th October, 1871. I have the honor to forward you, under separate cover, plans and sections of the proposed railway from Tokomairiro to Tuapeka. I only received them this morning, so have no time to report fully on the line. I will, however, do so by next mail, by which time you will also receive Mr. Barr's report and estimate. In the meantime I send the following figures taken from his estimate : — Average Cost per Mile. £ b. d. AVorks on line and engineering ... ... ... ... 4,975 10 9 AVorks, engineering, and land ... ... ... ... 4,998 1 7 Works, engineering, land, and rolling stock ... ... ... 5,148 6 3 I have, Ac, W. N. Blaie, The Assistant Engineer-in-Chief, Wellington. District Engineer.

No. 6. Mr. W. N. Blaie to Mr. J. Blackett. Sic,— Dunedin, 27th October, 1871. I have the honor to enclose herewith Mr. Barr's report and estimate on the Tuakepa Railway. In consequence of other engagements he was not able to give them to me till this morning, consequently I have had no time to supplement the report by any of my own. I will, however, endeavour to do so by next mail; and in the meantime if you want explanations on any point I will send it by telegraph. I have, Ac, W. N. Blair, The Assistant Engineer-in-Chief, Wellington. District Engineer.

Enclosure in No. 6. Mr. G. M. Baer to Mr. W. N. Blaie. Sib, — Roads and Works Department, Dunedin, 24th October, 1871. In accordance with your instructions, as per memorandum 11,244-12, 4th August, 1871, I have the honour to inform you that I have had Parliamentary survey executed of the proposed railway between Tokomairiro and Tuapeka, and now beg to report upon the engineering points involved. The line leaves the Otago Southern Trunk Railway at 36 miles 6 furlongs from Dunedin, and adjoining the present main road from Tokomairiro to Tuapeka, and proceeds across the plain to tho gorge through which the south branch of the Tokomairiro River flows, proceeding up it to the confluence of the Valla Burn, thence ascends the gully thereof to the watershed, separating that water from the Manuka Creek. The summit of this saddle is 48269 feet above the commencement of the line, and too high to be passed in open cutting, consequently a tunnel of 670 yards is proposed through to the drainage ground of the Manuka Creek, at that part known as Gardener's Flat. Before fixing upon this line I considered fully the question as to whether or not the gorge of the lower part of the Manuka Creek, up which the present main road runs, would be suitable for a railway; but I found that owing to its rapid rise at that part, being from 1 ill 15 to 1 in 35, and that the gradients could not be materially improved by commencing the ascent at any distance back from the junction of the creek with the Tokomairiro River, except at an enormous outlay, and that, moreover, the works for nearly two miles would consist of rock-cutting through a narrow tortuous gorge, I came to the conclusion that the line as surveyed will give a much better gradient and at less expense than could be obtained otherwise. The line, after passing through the tunnel, continues up the Manuka Creek the whole way to the summit at the Round Hill Saddle, where the ground is 714 feet above the beginning of line, and the formation of the railway is proposed to be 59554 feet above the same point in a distance of 9 miles 111 chains. With the exception of 65 chains at the junction with the Southern Trunk, and at A to to, which are level, the line is constantly rising towards this summit, so that nothing is lost by intermediate falls. The gradients on this part, which is undoubtedly the worst on the line, vary from 1 in 325 to 1 in 46, the latter being the ruling gradient of the railway. The saddle at the Round Hill will be pierced by a tunnel 250 yards long, after which the line descends to the valley of the Waitahuna River. It will cross the stream upon a pile bridge in five spans of 25 feet each, about 12 chains further down the river than that carrying the present main road, after which it will continue up the valley of the Waitahuna River to the first main gully leading northwards, up which it will keep at no great distance from the present road until it reaches the high laud forming the watershed of the AVaitahuna and Tuapeka Rivers, where it attains an elevation of 57611 feet above the starting point, or within 1943 feet of the height of the saddle at the Round Hill. The ascent to this is, however, very easy, there being only a length of 1 mile 25 chains so steep as lin 46. This part will be in open cutting, a tunnel being unnecessary. At 18 miles 40 chains the descent towards Tuapeka commences, and is accomplished in gradients of 1 in 46 for a mile and a half, and the remainder to terminus is upon gradients of 1 in 90, 1 in 55, and level. The terminus adjoins the Athenaeum Reserve in the town of Lawrence, in a