123

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"Various reports describe the character of the deposits at Humphrey's Gully, and indicate the prospects there before the company. That the prognostications made have not been fulfilled is true ; but these on the whole might have been of too sanguine a character, for though the facts of one day or a short period may be perfectly true, if they are taken to indicate the results of several years' work the chance has to be considered that the material may not be equal throughout in richness, and also that usually there is a falling-off in the value of the results, seeing that work is usually commenced where the ground is known to be good. Of these reports, the last, by Mr. Cox and Sir James Hector, may be here given. In a report dated March, 1884, Mr. Cox says :— " ' Since I last visited this claim the company has been greatly increased. The original company was wound up with the view of amalgamating with two other companies, known as the Miners' Amalgamated and Clarke's, the whole property now comprising 200 acres of ground, in which the thickness of wash-dirt varies from 150 ft. to 500 ft., the quality being alluded to in a former report.* " ' The principal operations of the company have consisted in bringing in a water-race, which is sft. square in section, constructed to carry 100 heads of water; and this work has progressed very favourably, with the exception of a tunnel near the outlet end of the race, in which the occurrence of a drift containing a great deal of water has for a time completely suspended all work. This difficulty is now, however, overcome, and the work of driving is now being carried forward at the rate of a chain a week; and, as there yet remain 20 chains to drive, it is probable that five months will elapse before water can be brought to bear on the face. The head-works from the tunnel upwards are now completed as far as the site of the dam, this including a flume of nearly three-quarters of a mile in length ; and the contract for the formation of the dam, which is estimated to take five months to complete, is to be let shortly. This dam has an area of 11 acres and 25 perches, from careful surveys, and is estimated to hold fifty-five heads of water for a twenty-four hours' supply, and by continuing the head-race over 100 heads is estimated to be available. As soon as this work is completed a constant supply of about twenty heads of water will be available, and this is to be directed on to the face which has been opened up from Macdonald's Gully, where a tail-race is being brought up by means of storm-water whenever this is available. A few trial sluicings have been made from time to time, the results of which have been very satisfactory; but, of course, no reliable information yet exists from which to estimate the yield per cubic yard of the field. " ' In view, however, of the large expenditure which is being incurred by the company, it will be well to mention some of the results which have been obtained in similar claims in America, in order to show the profitable nature of this form of mining when efficiently managed. Companies have sluiced wash from 40ft. to 260 ft. in thickness, with a yield from lfd. to 9fd. per cubic yard; and the amount of gravel moved per day varies from 2-73 to 20-36 yards per miner's inch, which, calculated at the rate of 6d. on the highest quantity of gravel treated, gives £20 sterling per head per day. The character of the gravel at Humphrey's Gully is such as to place it most favourably in the scale, and probably as much as 20 yards per miner's inch can be moved, which will give a total quantity of 16,000 yards per day, or 4,800,000 yards per year of 300 days, for twenty heads of water; or, when the total supply of 100 heads are in, the total quantity moved would be 24,000,000 cubic yards per year if full work could be obtained; and guarantees at least a very large quantity of gravel will be treated in which even a very small return would pay. " ' The works throughout are of a most substantial character, and have all been well and carefully constructed, and in the course of about six months should be so far completed as to allow of mining operations being commenced with about twenty heads of water available.'+ "In the preface to the same volume of reports, the Director, Sir James Hector, dealing with the same subject under head of ' Hydraulic Mining in Westland,' makes the following remarks : — "' This will be the great industry of the future in Westland. In former reports I have pointed out the distribution of the gold-drifts, and the manner in which the enormous discharge of water from the alpine sources had rearranged and concentrated the auriferous drifts that had given the enormous yield of gold in proportion to the number of miners which has so characterized the Westland Goldfield.J "■■' But this very violent action has, by cutting deep river-channels through the first-formed golddrifts, left undisturbed large areas of these drifts at a level inaccessible to the ordinary drainage systems. By the construction of water-races, and by the system of hydraulic mining, the re-sorting can be effected artificially and with profit. I had an opportunity of inspecting one of the most promising of these adventures about twelve miles from Hokitika, where at Humphrey's Gully all the small claims are now being amalgamated, so that about 200 acres is held by a company in one block. It forms a triangle in the junction of two tributary valleys to the Arahura Eiver, so that it lies favourably for getting rid of the tailings, which is the most important element in the success of a sluicing claim. The thickness of the gravel is from 150 ft. to 500 ft., as the bottom on which it rests dips into the hill, which also rises rapidly on the surface. The gravel is of two kinds, b and c, which rest on a, a silt clay with lignite seams, which passea downwards into the blue reef§ or marine

" * With reference to the quality of the wash-dirt in the report alluded to (Geological Reports, 1882, p. 54), Mr. Cox says no more than that the gold is of a coarse description, and that gold was present in every prospect taken from the face, no matter from what part of it. I have since been informed that many such prospects may be washed without finding a colour of gold. The gold is generally fine." " f Geological Reports, 1883-84, pp. 90, 91." " J I have quoted Sir James fully on this subject in the preceding and succeeding parts of this report, and the reader is referred to these extracts from his writings for the fuller descriptions above indicated." " § This is more exact information than I could obtain, probably on account of the present condition of the claim. Some time since a large fall from the face took place, and when I last visited the claim the fallen material had not been removed. I saw angular glacier or sub-glacier matter in beds and scattered through the laminated clays on which the auriferous gravels rest, but no beds of lignite were noticed by me."