THAMES GOLDFIELDS LEVEL SCHEMES.

New Zealand Herald, Volume XXIX, Issue 8854, 16 April 1892, Page 3

THAMES GOLDFIELDS LEVEL SCHEMES.

TO THE EDITOR. Sir,—As various suggestions have been made in your paper to increase the prosperity and uplift the present mining depression upon the names Goldfielda, and as discussion has been invited, I beg to submit, with your permission, a ,i amended or high-level scheme, which, taken into consideration, would be of great benefit to those interested in mining, on the score of economy, and will prove in a shorter period the lower strata and open up an extent of country embracing both hidi and low-level mining. Since the Thames goldfields have been opened, mine managers, as a rule, have been afraid to tackle the main slide in low levels, except in one instance, which failed through mode of procedure and inadequate appliances. If managers, in driving upon reefs, came in contact with the main slide, the work in that direction was invariably suspended. No attempt was made to pierce the above, ami discover the continuation of * m reef on the upper side. The cry was, 100 much water," " Drown out the mine," etc., even when pumping appliances were at band. Iherefore, the main slide lias become the mine managers' " bogie," and the country at a deep level upon the upper side is, to the mining world, a sealed book, or bete noir, to the present day. In actual cases main reefs, highly auriierous, have been followed to the slide. The latter has severed, thrown, or distributed the lode either right or left. Splendid specimens in portions of the scattered lode have been obtained upon the hangingwall of above. The queries are: Were these lodes (as found) formed after the down throw or previously ? Were the lodes connected preceding the downthrow? Present appearances indicate favourably. The dis- < turbance of the lodes at point of rupture, the distribution to the right and left denotes a previous extension and junction, also the proof that we have auriferous country immediately above and below the fault. Some mines in the shallow levels have driven upon lodes up to the slide with ill-success, and alter parsing through the slide hafe picked up the lode and procured more gold than below. lam not considering small leaders, but such as the main and strong lodes of the Moanataiari, Caledonian, Cambria, etc., which have yielded such excellent returns, ihe opinions of many possessing mining and geological experience are that the continuation of similar lodes will be found at the back or upper side of the main fault (on account of the snbaqeous formation of the auriferous series) more intact, and live to a greater depth and prove auriferous on account of no major disturbances likely to exist to throw the lodes from their true course as exemplified in the area below the fault. If the above should prove true, and there is no practical evidence to the contrary, then we have an enormous area (unworked for years) at our disposal in virgin country at low level, or, as a recent geological report states, " about a mile and a quarter wide north-eastward to the upper parts of Tararu and Otonui Streams, and thence onward in the direction of Mercury Bay." Is it to be supposed thatfif all the former rich lodes, i found below the slide at low level, some are ; not to be discovered on the upper side of similar character? Common reason ought to decide that question. SoeGoldiiclds' Report, ISS7. pages 32 and 33, giving plan of Thames goldfields, shewing network of drives, etc., trending towards slide. The most learned geologists, practical mining experts, also the well-established laws of " Displacement of Lodes" by faults in auriferous country, point to an affirmative conclusion. Good gold is daily found (in the hills bordering the upper side of the fault at shallow levels) from the Kurauui to the Hape Creek. Why not below? In the early days shafts were I sunk above the slide to shallow depths, and payable gold obtained. No further sinking or exploration could be undertaken on ac- . count, of inadequate drainage appliances, the miners being what is termed " drowned out." . 1 maintain if quarter of the capital, labour, and machinery for drainage purposes, as expended upon the flat, had been transferred to the sinking of a low level above the slide, and the latter tunnelled, also the Long Drive tunnel kept advancing in the proper direction, the Thames goldtield would not be in the depressed state as it is at the present day. My proposition is to combine a shaft and tunnel scheme. I will commence with the ; former. The main shaft to be sunk above ! the main fault in the Moanataiari or Waiotalii Creeks, ami contiguous to the Long Drive tunnel, the latter to be ultimately connected. The depth to be GOO feet, more or less. At every 10!) feet chambers to be formed, and prospecting tunnels driven in the direction, and, if possible, immediately under, the Long Drive tunnel. By this means connection can be made from the various levels with the latter tunnel for ventilation, blocking out, extension of crosscuts, and also for the purpose of obtaining correct records of the country in the neighbourhood, showing the thickness, strike, dip, and nature of various strata and reefs for future exploitation. These geological surveys to be made periodically, added to a main plan, deposited in the Thames -Mines Office, and open for public inspection. If this system bad been carried out formerly, some thousands of pounds would have been saved in prospecting and erection of machinery in ground of a barren nature.

'I'd resume : The machinery to consist of adequate pumping and winding plant driven by steam, water, or other applicable power. The whole to be of the latest design, embodying noncomplexity ot gear, combined withcontructural strciigh, economy in fuel cousumplion, wear and tear. A plant strictly fulfilling the above conditions would not require to be of a ponderous character, and the working expenses per ratio would be considerably less than any existing machinery of a like character. The shaft could be carried down to some depth, cither by temporary winding machinery for baling, or an approved steam pump, during the preliminary stages, pending the arrival and erection of the permanent plant. In some mining districts or New Zealand and the Australian colonies, crushing and other milling work is in abeyance during the dry seasons, on account of scarcity of water. In the wet months operations are recommenced, when it copious supply is conserved by the construction of dims, adjacent to the main watersheds and surrounding drainage areas. Hearing this in view, I should, for the purpose of economy in pumping and winding expenses, suggest the same expedient (if practicable), as follows : — Construct au impounding dam in either the Moanataiari or Waiorahi Creeks. There are places well suited for the purpose. The work could be carried out economically, the materials being at hand. .Side catchment races commanding the various tributaries to lead into the Whau dam) to ensure an extensive drainage area. These latter are easily constructed, and would not interfere with mining. In case of a wet season, to show the utility of the scheme, supposing a dam, situated up either of the above creeks, commanding 801) feet head, pipes leading from the latter down to the pumping station,the water acting upon an efficient hydraulic motor, say a small catchment area of ftj'J acres, one inch rainfall of "24 hours would furnish at the above station 120 horse-power for about I*2 days. The waste water from the hydraulic motor being led in pipes to the flat, would yield approximately 60 horse-power for about 12 days also. The rent of the same, if the wet season extended, would materially assist the payment of the engine-driver's wages, etc., also fuel economised. The hydraulic motor and gear would be easily disconnected. The cost of the whole, as mentioned, would not be much, commensurate with the great saving in working expenses. I have not been able to obtain reliable data regarding the amount of rainfall in the wet season, but J should think at the least, one inch in a week. If circumstances admit, I would suggest that a tunnel be carried through the slide. The country forming the latter could be pierced from the upper side with greater success. The extension would be with the " flow." The chief obstacle to contend with in this instance is the superincumbent weight and a limited " face pressure." If attacked from the " toe," or lower side, greater difficulties would occur on account of tJie inclination of the main fault, causing a downward, lateral and advancing " How " of soft " pug " and water. The tunnel to be at such a depth as to ensure connection with the most advantageous existing levels on the lower side.

x should imagine that the slide " cannot be of great thickness on account of the obliquity of the lower bed," and the tendency of the upper mass to adhere closely in the descent. At all events, material advantages would accrue of draining the upper and lower areas, affording access from the present low levels. The Long Drive tunnel to lie extended at the most convenient angle to intersect any lodes speedily, and to facilitate the latter being driven upon. The ventilation would be as per shaft, or a systematic method economically arranged. Re financial arrangements. As the scheme described would benefit the Auckland and Thames mining community, and open up a large area of untried ground, and also connect the upper and lower portion of the goldliold, undoubtedly infuse vigour in mining operations, and induce foreign capital, I would propose that a company be formed, with a capital of £30,000, with 00,000 shares of 10s, unpaid. The Borough, County Councils, and General Government to be asked to subsidise per ratio on amount of progressive work performed, either by periodical payments, or lump amount," or other suitable method. These latter amounts to be deducted from the chief capital, thereby reducing the indebtedness of the public shareholders. If legal, the Borough and County to have representatives upon the Board of Directors, the other members to bo elected by

the shareholders. The mines along the route j to be defined, and worked to a certain depth j by the individual companies, the remaining depth to become the property of the new company, or the new company to have a right to all minerals in the portion they are working; the size of block to be defined. If work in any block- is suspended by the new company, the surface companies can enter and work the same, and allow tributers, by subscribing for any uualloted shares, or other defined charges made by the new company. This includes winding, pumping expenses, use of tunnels and rolling plant, etc. Another system could be adopted :—ln any tunnel, the new company has driven, all the lodes or portions thereof found within a prescribed circle or square section from centre of the tunnel, to be the property of the new company. Or mining companies could combine to extend a crosscut, level, or other works to suit their individual mines by paying the necessary charges, and letting by contract. This would reduce the cost of each company to a minimum in prospecting work. To prevent areas being taken up for purely speculative purposes, with no intention of developing, to prevent" " shepherding," and other means adopted of non bona fide working, I would propose a properly-constituted Board to assess non-subscribing or non-working companies within a certain distance of the furthest tunnel face driven by the new company under the drainage clauses, or adopt a defined method to all companies, viz., reduced charges to subscribing and working companies in the new ground ; the non bona ride working and non-subscribing companies full rates. One of the greatest mistakes perpetrated upon many goldfields, and keeping away foreign capital, is the practice of pegging out areas, with no intention of working, and other methods adopted to " hedge" auy fresh capital. I would suggest the Long Drive tunnel to be transferred, by purchase or otherwise, to the general Government, and conducted under regulations similar to the extensive Government tail races, sludge channels, and oilier mining works in other portions of the colony, or a right of entry be granted to the new company, with existing rights. These suggestions are brought forward not altogether with a view of ultimate adoption, but more for perfecting and improving future arrangements upon a satisfactory basis if carried out. I might mention if operations are managed systematically, and an efficient plant ; purchased judiciously, having entered into ! approximate calculations, that the expenses will not approach the capital by a long way. The scheme, as promulgated, will be more expeditious, economical, reach the second strata sooner, than any project hitherto submitted to the public. One thing to consider is : It is more economical to sink, say, 600 feet above the slide (I think the second strata will be met with before that), and pick ii)) the auriferous lodes, which we are nearly certain exist there, or to sink 1000 or 1500 feet upon the flat or lower area, in ground where we have no existing proof that auriferous country will be met with. In a paper by Mr. James Park, F.G.S., Thames School of Mines, entitled *' The Geological Structure of the Thames Goldfields, it is stated " that a bore put down on the upthrow side of the fault would explore lower country, and reach the old floor or the basement rock in a shorter distance, than a bore put down upon the foreshore, which has been carried down in recent times several hundreds of feet from its original position." In alluding to the Buck reefs, so called by the miners, some of which exist above the slide, and reach the vicinity of Punga Flat,&c, Mr. Park states, "Besides these gold-bearing veins, the auriferous series contain what are locally termed ' Buck Reefs.'" In Mr. Cox's reports of the Thames Goldfields, the latter states these deposits are crosscourses, but Mr. Park denies this most emphatically, and with certainty, as follows : " But their character and behaviour are altogether different from those of crosscourses. They do not deserve that name. Tests of samples from a number of these reefs at the School of Mines in all eases proved the presence of gold and silver, the bullion in a few instances being worth as much as £11 per ton." Here we have distinct evidence of the auriferous character of the above, which leads us to hope they will greatly improve in depth. Even if £2 per ton was realised, being of such great width, would be remunerative, when we know that thousands of tons of quartz have been crushed upon this field only yielding a few pennyweights per ton, anil yet payable. In conclusion, if Thames and Auckland combined with one heart, one mind, I am certain matters would be speedily arranged, and work started at once, pending the manufacture and erection of machinery. The advantages are : Effect the connection of the upper and lower area at the lowest existing levels : develop a mass of hitherto loeked-up country, that would take years to exhaust ; restore business confidence, and probably bring about the former prosperity of our goldfleld.—l am, etc., Progress.