THE GOLD DREDGING INDUSTRY.

Otago Daily Times, Issue 11505, 18 August 1899, Page 2

THE GOLD DREDGING INDUSTRY.

IN ITS PRACTICAL, ECONOMIC. AND GENERAL ASPECTS.

(Br Otrn Special'Repobteb.)

XXVIII.

.SUPPLEMENTARY AND GENERAL,

_ Almost the whole of the dredging Belds in Otago where active operations are carried on having been described, after being visited and inspected, there remains to be noticed quite a host of localities in which dredging .has only been projected. As a considerable amount of attention is directed to those places by the general public a tew remarks concerning them will be welcomed. °

CENTRAL OTAGO.

Starting with Central Otago, where dredging is farther advanced than in most other localities about to be attacked, it may be accepted that there are quite enough ventures already set up to test the characteristics and perhaps the real value of the ground.. They ; avp served the purpose of showing that gold exists in quantities to pay with suitably appointed dredges however, with the exception of a few isolated cases no great or phenomenal returns must be expected. This is principally owing to the gold originally in the ground having been already got. Most of the ground here is shallow and dry, and therefore easily v.-oiked. All such ground had been turned over repeatedly by the white man when the Chinamen came in to finish the job, working everything that would pay 6s or 5s a week. Much of the ground was sluiced, and here, of course, the dredge is completely anticipated. Where there is solid untouched ground to work tilings may probably bo different, and it is reasonable to suppose that plenty of such country is to be found, too poor to have tempted the alluvial miner, and yet rich enough to pay very handsomely for dredging. Had it been possible to work the Kawarau and Molyneux in the same manner, as most of the ground in Central Otago, the dredges would not have had the chance of the good things they came across.

It may safely be accepted that there are now sufficient ventures set on foot in Central Otago to prove its value, as a dredging field, and it will be wise' to let these ventures set on foot prove the best method of working the ground, and so settle the question of its payability. The chief trouble in Central Otago is that dredging there is essentially dry land dredging—that is to say, dredges are confined to one particular spot, out of which they cannot be moved to any great distance without being taken to pieces. For this reason it is imperative that parties placing upon the market dredging claims in Central Otago should be prepared to prove past a shadow of doubt that the ground selected is payably auriferous, and also produce such evidence as makes it clear that the real nature of the ground is perfectly well understood, so as to adapt the dredge and her. appointments to the characteristics of the ground, leaving nothing to accident or chance in the construction of the dredge.

The position of Central Utago, simply stated, is that the dredger will have to deal with worked ground," and a good deal of ground so poor that it may be described as hovering about the minimum point marking oft success from failure.

THE KAWARAU RIVER.

An independent article dealing with this river had already appeared before the pre-

sent scries was begun. It, therefore, only remains to summarise what has already been said. Leaving out the lower portion, from the mouth of the river up stream, inclusive of the Magnetic Company,'there is the part in the rocky gorge extending to the Roaring Meg. In the whole of this portion there is not a better point for trying the river, both for gold and to settle the question whether or not tile ground be dredge<ible, than is offered at. the lower end of the Voltaic claim, recently taken off the market. . The Magnetic No. 9, attempts to, prove the same problem under greatly increased difficulties. At the Magnetic No. 2 work is started immediately above a biaik of big stones. At the lower end of the Voltaic boundary the river falls over a ledge of bare rock,'upon which no ; big stones could lodge withoutVbeing seen. This fact, however favourable it may be for starting work, doesn't therefore proye that the whole or any appreciable portion of the Voltaic claim is dredcenble. . Tint sis a question for actual tests to decide. All the rest of the Kawarau here

spoken of, with the exception of the Voltaic claim and option, is extremely risky ground to deal with. The position of this part of the Kawarau River and that of the two claims mentioned is that in the Magnetic No. 2 the company start upon and above a bed of big stones in their attempt to bottom ground 30ft to 35ft deep. . The Voltaic instead proposed to start upon the bare bed ror^. showing in the broad light of day which may or may not have proved workable. It does not require .a very high degree of mining knowledge to si-.y which company is the more favoured by circumstances.'" The fact that the future' of the Kawarau is seriously affected by this position of affairs must serve as an excuse

for this rather lengthy notice. From the natural bridge to the Nevis Bluff recent : trials have proved that some disturbing and unaccountable influences have been at work, and it may be reasonably questioned whether this portion of the river is payably auriferous. The stretch from the Nevis Bluff to

;he junction of the Arrow River with the

Kawarau may be dredgeable, and if moderately so may be second only to.the lower portion of the Kawarau where the Electric and Magnetic are situated. The best portion of this stretch is certainly that extending from I)eep Creek to Andrew Reid's slip, a short distance above the Kawarau bridge. From the Arrow Junction up stream to the junction of the Shotover

the Kawarau is a very doubtful field. As is well known, this portion was the scene of the dredging boom that lad to the, disaster' of 1890, out of which grew the present vigorous and huftithy development of the dredging industry. The nature of the river here is totally 'different from what it^ is at and below the Arrow Junction. The gold lies upon a false bottom of coarse lake wash, and is contained in a layer nob much more than one or at most a few inches thick, the overlying and underlying wash being completely' barren. There are a few. instances where the banks of the river contain gold, and no doubt will pay a moderate return for a suitable dredge. Where thesa banks do not exist, and the dredge has to depend upon the seam of gold in "the river only, nothing but disappointment need be expected. One dredge could easily clean up an acre in a week for returns that might possibly leave a small surplus for dividends, supposing the company had started dear of debt. There are, however, two exceptions to theso remarks. One is near the mouth of the Shotover, where the Golden Link, working with the Franktors .Reach disdge, obtained some very good returns. A party of tributers took over the oonc&rn, and "made as much as £1 per j day per man for a number of months. How much there is of this ground it is difficult to say. The other exception is at the mouth of the Arrow River. Very rich, coarse, and even heavy, gold was got upon both brinks of the Kawarau River, from which it may be,safely argued that the river bed is also rich in the same kind of gold, which ran up to soz nuggets. All that is required here h a dredge capable of going to a great depth, say, 40ft, where rich gold is sure to be met with, as it was traced down to the water's edge on both sides.

TKE SHOTOVER RIVER.

It would he a mistake to class the Shotover with the dredging fields of Otago. The river from Arthur's Point upwards, for a distance of 30 miles, is no more fit for dredging than for steam navigation. From Arthur's Point down stream to the Lower Shotover bridge, about five miles, the ground lias been proved by the Sew Hoy dredges recently at work 'there, and since then,, with even better effect, by the Golden Terrace Company's two dredges, one of which has obtained regular and satisfactory returns for many months past. The two dredges of this company are now making for the lower boundary of the claim, where it is supposed better ground exists than has yet been worked in the neighbourhood. This speaks well for the adjoining claim, the Shotover Gold Dredging Company, which extends from the lower boundary of the Golden Terrace claim to (he Lower Shotover bridec. Isc-

low tile bridge there is about a mile of river and benches, but it is difficult to say anything of the value of this ground as it has never been properly prospected. The low bank, ■on the east* side of the Shotover, is known to contaiu gold that might pay for dredging, fair prospects having been got there so long ago as thirtyseyen years. The proposition of Mr James M'George, and the newly formed Dunedin 'syndicate, to bore at Arthur's Point for another bottom may be commended as a praiseworthy prospecting experiment, but faith in the success of the scheme is shaky among all who have a knowledge of the ground. While mentioning the Sew Hoy- Company it may be mentioned that seldom did a newspaper show better judgment or more courage than did the Otago Daily Times and. Witness, when nipping in the bud the proposal of floating a gigantic concern some years ago' that did not in any way warrant anything like the proportions of the projected scheme, and it may be added that seldom was a newspaper more justifiably vindicated by after events than was the Otago-. Daily Times in that instance. Whatever show for success there may be from Arthur's Point to Lower Shot.over bridge, the portion between the bridge and the Kawarau being merely an estuary of undefined extent, is, to sv/ the best for it, exceedingly doubtful ground. It has been proved by bore holes in one spotbut in one spot only—to bo a mere diluvial quagmire. That part of the Shotover from Arthur's Point upwards has been tried , since 1868 down to 1898 by quite a number of dredges, not one of them turning out anything like a financial success. The last attempt was made by the Sandhill Electric dredge, managed with consummate skill and care by Mr R. 'White, who, being an experienced electrician, worked atid lit the dredge at a minimum of cost that no other dredge has ever touched, and then she did not pay. The reason of this is not far to seek, and is wound up in a word or two—" hard rock." i Watson arid party were, until stopped by the recent frost, cleaning up some bottom gone over by the dredge, and made very good wages under great difficulties. This does not in any way ; reflect upon either the dredge or the management. It simply'confirms what has long been known to be the case—namely, that the dredge bucket cannot deal successful ly with, gold upon a hard, or even moderately hard, bottom. Besides this and other reasons very palpable to the average mining mind, why dredges did not, and are not likely to supcee'd, upon the Upper Shotover,' there' is the fact that there is no ground available for dredging claims, the whole of the river being pegged off in claims, worked, or to be' worked, by Smith and Son's hydraulic suction pump, a far superior and cheaper process than dredging can ever become

THE GOLDEN TERRACE DREDGING ' COMPANY (SHOTOVER). . .

Tiie'Shotover Big Beach dredging boom has a history of its own. In was in 1888 when Mr Sew Hoy, the well-known Chinese merchant, from information received from a number of his countrymen, started dredging at Big Beach, which was at one time one of the richest spots on the Shotover. Dredging from the beginning was a success, and the half-ounce per hour i^'.urns, which had a good deal to do with the Kawarau boom, which burst in 1890, will be remembered by many. Excitement ran higher and higher as dredge after dredge was built by the Sew Hoy Company, until there was a fleet of four dredges on the claim. However, it was soon found that there was not room enough fc; the four boats. In the meantime the Talisman dredge, working at Tucker Beach, had to succumb, being director-managed from Duncdin. Operations were suspended, the dredge sold, arid the claim abandoned. At this juncture Rig Beach dredge No. 4 was ■floated down to the ground deserted by ■the Talispian dredge, through the gorge below Arthur's Point, many people predicting disasters of all kinds to dredge and men on board, owing toy the rough character of the gorge, but Mr Anderson, how dredgemaster of the Golden Beach dredge, Molyneux, safely. piloted the boat on her dangerous passage. Arrived1 at Tiicker Beach, the dredge failed to retrieve the varying fortunes of the Sew Hoy Big Beach Company." The cost of the four 'dredges, the limited area for them to work, and the, .big, steal of 104oz of gold—never yet cleared up —sealed the fate of the Big Beach Com-. : parry, and it went into liquidation. , , Out of. these troubles rose the Golden Terrace Dredging Company, which took over the 100-acre claim and dredge at Tucker Beach and started work. Fair returns were obtained from the start, and, encouraged by the gold won, the company bought the Big Beach dredge No. 3—a sister boat of the first dredge. This boat' was also safely clown from Big Beach, about a year ago, and had been constantly at work without, however, getting a great deal more gold than to pay working expenses and other outlay.

The Golden Terrace 'Company started with a capital of £5000, in £1 shares, 15s lof which was paid up. For this there are to show-two serviceable and well-appointed dredges, and dividends amounting to 4s per share. According" to all indications, both the dredges of the company have so far been working,the poorest ground in the claim. The bulk of the .gold got was obtained by No. 1 dredge, which has averaged from 16oz to 17oz per .week.... Each of the two dredges cost originally £3500, and they are still as good "> nd strong as ;they were when new. The company... is clear, ! of debt, and there is every probalitiy'of: very good ground being met with when the two dredges get a little lower down stream. Kact dredge is managed by a dredgemaster. ■M,r.R. Henderson, who is a shareholder in the company, and who has had 10 years' ; dredging experience on the Shotnvor,* pas-' .sing through .-,11 the glories and vicissitudes of the Sew Hoy Big Beach Company, acts as local agent, and, being a blacksmith by trade, does most of the repairs required to mining gear and machinery, for which purpose there''is a: complete blacksmith's arid; engineer's shop on the ground, including a powerful shearing and punching machine. Of the 17 men employed by the company, nine are shareholders in the venture. There is also: a furnace on the ground for retorting the amalgam, as the gold is so fine that to separate it from the black sand quicksilver , has to" be used. "After No. 2 dredge, had been shifted to Tucker's Beach an additional claim oTSO acres was taken up, so that the company now holds in all 150 acres.' .

A description of one dredge answers for the other, both being built after the same [ design. The only' difference there is is in the gold-saving' plant, which 'will be specially dealt with. Both boats, with engines and everything complete, were furnished by John Anderson, of Christchurch, and a use of 10 years testifies to the excellence of! the work.' Both dredges are in a perfect; state of preservation, and are kept in. a most exemplary order. Nine men are employed on board dredge No. 1. The pontoons arc 90ft long by 18ft wide, over all, and 7ft deep. Aft the well the two pontoons form one compartment, in which are placed the boiler and engine, an arrangement which leaves the decks clear of encumbrances. The pontoons are of. steel.-'and strongly built, or they could not have stood the rough journey through the Shotover gorge. The engines are of 26 horse-power nominal, and the boiler works up to 801b pressure per square inch. The laMder is 72ft long, and the buckets hold 2£. cubic feet each. It is intended to replace them, by larger ones before long. The winches are after the capstan pattern, worked by the engine from the main shaft, If they are slow, they ensure the perfect cleaning up of the bottom, and are other-.

wise easily managed. Instead of steel wire ropes,'chains are used, the only drawback being their weight, in hauling them about when shifting the position, of the boat.

The gold-saying plant on this boat is a sluice-box 50ft long by 3ft wide. The buckets dump the wash upon a grizzly or grating, which sift out the big stones. They afe discharged by a stone shoot, connecl-

ing with the grizzly, without ever being allowed to enter the box. The grizzly also answers well for breaking up the clay when met with. This arrangement, together with the nature of the wash, which is free and easy to work, and comes up in full buckets all the time, necessitates the attendance of a man at the boxes. To the tail end of 'the. box is fixed a reverse box,

cliiefly for a test of the tailings, but it is found that the loss of gold from the main

box iB insignificant. The dredge is now reworking some of the ground previously gone over by the Talisman dredge, from which very good results are obtained, showing that the gold-saving plant is of a superior order. Mr E. A. Johnston is the

dredgemaster on dredge No. 1, originally No. 4 of the Sew Hoy Big Beach dredges. Wnrl- an 'flip fJ.VMen Terrace cliiim was

started in December, 1897, with this dredge, and has been carried on without n loss°of time of 24 consecutive hours. Even the lato severe frost was not allowed to Break full working time. The depth of the ground is from 15ft to 17ft, but, the bottom being somewhat irregular, the buckets require constant watching. The face is taken about 100 yds wide, which appears to be the width of 'the run of gold. The gold is fine, and requires' care in saving it, but it weighs well. Mr R. T. Wheeler is the Dunedin secretary of the company. Dredge No. 2, whicli was dredge No. 3 of the Big Beach Company, is in every respect the same as dredge No. 1, the only difference, as stated, being confined to the

gold saving apparatus,

whicli upon this

dredge consists of a cylinder and tables. Here, then, we have two exactly similar dredges working ground of nearly the same nature, contrasting the relative value of the sluice box with the cylinder or screen.. Both box and cylinder are worked and watched with consummate care and ability, and the loss of gold from either is reduced to the lowest possible minimum, proving that so far as efficiency goes both are on a par. As a matter of expense there is also not much difference, the cost of an" additional man per shift attending to the box about balancing the price of the cylinder the average length of the life of which is about two years. The gold-saving ap: pliance on drecige No. 2 is the invention of Mr W. Shaw.

To begin with the cylinder, the perforations are gin in diameter for nearly the whole length of. the cylindet, which is 15ft, with a diameter of 3ft 6in. For a few feet near the mouth the perforations are increased to -Jin. Two lengths of chain (iiri links), attached to a swivel, reach the whole length of the cylinder, and by virtue of their weight keep on the bottom, rubbing the-gravel over the perforations, and preventing them being blocked. The chain is also a great assistance in breaking up clay when present, and. aids in the perfect washing of the gravel, as it delays the too free discharge of the wash. Beneath. the cylinder is a Board lined with cocoanut matting, considerably less .in width than the diameter of the screen. On either side of the revolving screen is a distributing box, dipping to the stern of the boat, catching the discharge from the screen, and paying it iiito a horizontal distributing box, which-feeds the fine gravel and gold to the tables on either side of the screen. By this arrangement not only the, gravel but also the gold is'so evenly distributed over, the width of the tables that as good a prospect can be obtained near the mouth of the screen as near the top end. There is also provided a trough, which, by overflow, regulates the supply of water for the tables, the trough being of a size to hold only just enough foij the supply of thetables, the surplus is paid back into the river. This obviates a gerat difficulty in the average dredging gold-saving plant, where, as a rule, there is no control over the quantity of stuff to be treated, or over the quantity of water to treat it, both quantities constantly varying, according to circumstances. The tables on either side of. the screen are of 12ft by 15ft superficial area, and are fitted with ripples of Mr Shaw's invention, consisting of light fencing wire, woven basket fashion, the length of the wires running across the- box. The ripples are placed upon cocoanut matting, and answer their purpose well. There is also a step table, with a drop of 9in, but the stuff is not allowed to fall over' the drop; it is paid into a distributing box, and thence on to the lower step. Very little gold, however, is got from thispart.

llr Shaw, who has a partner (or more) in the invention, has patented his appliances, which are certainly well adapted to the screen system of gold-saving, and may safely be recommended to the'1 attention of dredging men. .

' Owing to no man being required to attend to the screen, there are only six men employed on dredge No. 2, as against nine on dredge >70. 1. .