ENGINEER-IN-CHIEE.

9

D.—No. &

From Waikouaiti to Moeraki the country is much easier, and the plans more definite, so the line has been laid down with greater precision. The following is a general description of its course :— Leaving the Government township of Hawksbury, near the middle of the lagoon, it rises on the slope to the east thereof, crosses the main road, and runs almost straight to the saddle, about 20 chains westward from the Bendigo Hotel. At this point the line trends eastward, re-crosses the main road, below Trigonometrical Station H and regains the flat in section 39, block 4, Hawksbury District. It then runs round the point of the spur into the Green Swamp and Pleasant Valley, striking the latter at the lower fellmongery. Pleasant Creek is crossed on Mr. Hepburn's property, and for the remainder of the distance up the valley the line keeps to the east of the road between the creek and the high ground. Opposite Mr. Douglas's homestead it takes a sharp curve eastward, following up the watercourse in sections 22 and 14, block 4, Hawksbury District, and enters Palmerston by the Manse Gully andJßimbrake Street. Leaving Palmerston, the railway runs due east for two miles, and crossing the Waihemo about two miles below the main road, it ascends to a saddle in the Horse Ranges immediately below Puke Iritai, and one and a quarter miles from Shag Point. The coast is then followed to a lagoon in section 14, block 2, Moeraki District, where the line bends sharply inland and runs down a gully to within 2 chains of the main road at the Kartigi School House. Erom this point to its termination at the junction with the branch to Port Moeraki, the railway keeps parallel with the North Road. The total length of line from Waikouaiti to Moeraki by the route just described, is about twentytwo miles, and for the whole distance the country is remarkably easy and suitable for railway construction. There are only two places where any " grading " is required; one is getting out of Waikouaiti, and the other is at the saddle in the Horse Ranges, tho height of the ranges to be thus ascended being about 130 and 150 feet respectively. The former can be run up and down with gradients of 1 in 60 or 70, but probably it will be necessary to have 1 in 50 on the north side of the latter. Any cuttings required will be through soft lime or sandstone. There are only two streams of importance to cross, the Waihemo River and Pleasant Creek. The former will require a bridge 150 feet long, and the latter one of about 60 feet. In both cases the sites seem suitable for pile-driving. A large quantity of shingle for ballasting could be got at the Waihemo River, and the district can produce stone lime and timber suitable for railway purposes. I will' not attempt to give an estimate of the cost of constructing a railway from Dunedin to Waikouaiti, as the country possesses peculiarities that prevent a comparison being made with lines already made or estimated. But from Waikouaiti to Moeraki this difficulty does not exist, and I would have little hesitation in fixing the cost at something under £4,000 per mile. With reference to the cost of making a further survey of this line, I think that a Parliamentary survey of the portion between Waikouaiti and Moeraki might be made in five or six weeks, by one party, at a cost of about £100, i.e., about £5 per mile, exclusive of office work. It is very difficult to estimate the- cost of making a detailed survey of the remainder of the line ; it will necessarily be very heavy, and the work will take a long time ; in which case it might be better o postpone it till the working survey is required, or make the Parliamentary survey of such a character as to serve for the working one. In connection with this subject, I might suggest the consideration of the question as to whether it would not in the meantime be advisable to divert the traffic of the Waikouaiti and Shag Valley Districts to Port Moeraki, by making that portion of the line. I have, <fee, W. N. Blaib, The Engineer-in-Chief, Wellington. District Engineer.

No. 2. REPORT ON THE WAITAKI BRIDGE. Mr. Caeeutiiees to the Hon. J. D. Osmond. Sib, — Public Works Office, Wellington, 24th November, 1871. I have the honor to submit the plans for a railway and road bridge over the Waitaki River, with estimates of the cost of each. 1. An iron plate girder bridge of 54 spans of 66 feet, each supported on piers consisting of two 4-feet cylinders of cast iron, filled with concrete, and sunk to a depth of 24 feet below the lowest water level; the under side of girder being seven feet above highest flood. The total depth from under side of girder to bottom of cylinder being 37 feet 9 inches. The estimated cost of this bridge is £57,988. 2. A wooden bridge of 44 spans of 80 feet each, supported on piers precisely similar to those of plan No. 1. The tension booms and the three end braces would be of jarrah timber, the whole of the remaining parts would be of totara. As protection from fire, a coating of gravel four inches thick, set in cement, would cover the whole floor, and the booms would be protected from the weather by a covering of zinc. The estimated cost of the bridge is £38,936. 3. An iron plate girder bridge of 110 spans of 33 feet each, supported on piers, each consisting of two sets of solid piles. Each set is made up of three solid piles 4| inch diameter, and driven to 24 feet below lowest water-level. The piles will be long enough to reach three feet above ordinary low waterlevel. An iron ring will be shrunk hot into the heads of the piles, and further secured by a set screw. On the rings a casting will rest which will bind together the heads of the piles, and act as a base for the upper work to rest on. A ring of iron shrunk in hot will also tie the pile heads together, and thus relieve the casting from undue strain. The upper work consists of a strongly braced iron frame, carrying a wooden cap, on which the girders rest. The girders are these already ordered for the bridge. 3