E.--0

1875. NEW ZEALAND.

TOPOGRAPHICAL SURVEY OF BULLER COAL FIELD, (REPORT ON).

Laid upon tiie Table of the House of Representatives by the Hon. the Minister for Public Works.

No. 1. Mr. W. M. Coopee to the ENGrNEEn-ra-CHiEF. I. —Wokk Done. 1. Dueino the past season, the survey has been extended southward from the point previously attained, to the summit of Mount Rochfort and eastward to Mount William Ridge, whilst westward it has been continued as far as the plateau country extends, leaving the sea face, the whole distance from Westport to Granity Creek, yet to be surveyed. The latter instalment was left over for work during the winter, when it would bo impracticable to carry on operations on the high ground, and is now being proceeded with as rapidly as weather will permit. 2. The survey has been carried on in the same manner as described in my former General Report, dated 15th June, 1874, with the addition of a major triangulation, and an exploration for coal. 3. The major trianguhtion consists so far of six triangles of from two to six miles in the side, the bearings being taken with a 7-inch transit theodolite. The trig, stations are built in a substantial manner of stones, except in one instance where it was necessary to use sods instead, forming a circular structure 4 feet high and 7 feet in diameter on top, in which is imbedded a strong iron peg 5 feet (3 inches long, with two cross bars at the foot, and a 4-inch ring bolted through the upper part to receive a pole. The triangulation is founded on a base line two and a half miles long, for the site of which a convenient place was found in a straight run in the first section of the Westport and Ngakawau Railway, thereby avoiding the expense which has usually to be incurred in preparing the ground. 4. The coal exploration has been carried on by Mr. R. B. Denniston with the assistance of one man, and has been extended over an area about coterminous with the whole of my survey on the coal fields. This work consists of carefully going over the ground after survey, and making as thorough an examination of the strata, their nature, dip, breaks, &c, and particularly the outcrops of coal, as can be done without excavation, with the view of being thereby enabled to mark upon the map the different areas of coal, their probable extent, thickness, and quality. I forwarded at the close of last year a report of his operations to date, and a map showing the results in that part of the coal field which he had then gone over, being the portion included in sheet 9 of the lithograph map. I now enclose his report for the period from Ist January to 30th June, 1875, and the results of his operations during this period are shown in tracings made from the field maps by Mr. Cox, when in Westport a few months ago. Ido not therefore think it necessary to make a map of them to accompany the report. 5. The amount and list of work done by me during the period embraced in this report are as follow: —Lines traversed, 95 miles; bush lines cut, 19 miles; number of major trigonometrical stations erected, 8; minor trigonometrical stations, 205 ; numbered traverse pegs, about 1,000; and aneroid observations, 1,970. The area of ground surveyed is about thirty-three square miles, say 21,000 acres; and the total cost, including an estimated sum for the plotting not yet completed, and the cost of some work done by me on the Mount Rochfort Plateau in November and December, 1873, will be about £1,400, being at the rate of Is. 4d. per acre. G. The amount and cost of Mr. Denniston's work for the same period are as follow: —Area explored and mapped, about forty-two square miles, say 27,000 acres; and the cost is about £420, giving an average of 3|d. per acre. 7. The total average cost of the work is therefore Is. 7£d. per acre; and, taking into account the mountainous and broken nature of the country gone over, and the minuteness of detail with which the survey has beeu carried out, I think the figure must be considered a low one. I—E. 0.