Hydraulic Mining in California.

Cromwell Argus, Volume V, Issue 264, 1 December 1874, Page 7

Hydraulic Mining in California.

■ubjec* was read by Mr Patriot Couriafeey, who has reoeatjf visited California, before the Hokltika lastitute nfewdays* ago : Gemetf ffif-fThe subjectof obtaining a proper supply of water for working the large tracts" of auriferous ground whiah exist on the Goast. has always been one in which I have felt the liveliest interest, and I therefore made it my special business during my recent trip through America, to make, the fullest enquiry into the* method adopted in connection with the extettstee hydraulic workings which., are uow in full operation l there. The present appears to mjS-tofhei a most suitable time for discussion Of the best system of hydraulic -■seem-; that severallarge water-races are -now in progress, and I presume, will one . day be completed. .Having been from the .. earliest settlement of the Coast intimately connected with its progress, and being still interested in its prospects, I am desirous of putting yon in possession of isucb infor- *• rattibn as "I have been able togaip from the experience of other places, and without pretending tp give you au elaborate treatise on the subject, L hope, that a practical narration of the facts.which have come under my notice, may be the means of assisting in the introduction of a more improved system of working than has hitherto been - -adopted on the Coa . . The present system of'ground sluicing in this country is so well known to you all, that it is unneces"siry forme to allude to it, and I therefore , purpose tp pass on to what I consider the improved system. In America the water is brought to bear at the highest possible point over the wash, and in order to retain the pressure it is then conducted through wrought iron piping of sufficient size to carry the quantity of water obtainable, to the face of the claim, where it passes through the hydraulic nozzle with enormous force. The present system of allowing the water to fall loosely on the face i-< a great waste of power, while the use of canvass hose is little better, owing to the great friction and waste of water from leaky seams. In order to work to the best advantage, the' greatest amount of pressure possible must be kept on ; this is accomplished' ly the use of iron pipes, and the patent nozzle, a description of which I will, presently give you. The iron piping • required for this purpose is of the simplest .. construction, and much.less expensive than the canvass hose now in use. The ;size of the'pipe'will depend upon the quantity of water intended, for use, arid the- thickness of the iron upon the pressure to be had. The nnteri«i generally in use is the ordinary malleable sheet iron such as is used here for chimney piping. . The gauge generally med is number 16s this is, sufficiently strong to bear the first 250 ft pres sure. Fourteen gnage will bear 300, and ten guage 400, and so on in proportion. The piping is usually made in 12ft lengths, each length to fit into the rest, and so retaining its bold by the pressure of the water. As a guido to the size of piping for use, I have seen ten heads of water having two hundred feet pressure, pass through a pipe 15in in diameter, with sin nozzle doina? great execution. In many places Bin pipe 2\ nozzle, 4 heads of water and 100 ft pressure is used. In order to preserve the piping from rust it should be dipped in boiling asphalte and tar ; where these are not obtainable a coating of ordinary gas tar will be a good substitute. Pipes thus preserved should with reasonable cire last a life time. Ten-inch pipe should, cost about 2s 3d per running foot, and .15in from 43-to ss. Iron "piping should also .be-used for fluming and cohveying water over deep ravines. Being not more expensive- in the first instance than wood, and as it does not require a constant.outlay to keep it in order it is consequently far preferable, is a rule, the pressure in this country is not very great, owing to the comparative evenness of the ground, consequently pipes made of ten guage iron would, in most cases, carry the contents of the largest £aces in New Zealand. * I am at a loss to understand why cast-iron pipes have been introduced far the Waimea Water Rice. In a country like this, where carriage i 3 a serious consideration, an enormous saving might have been made had wrought iron pipes l»een substituted. Pipes of this malleable iron one-eighth the thickness of those lying in the square would answer the same purpose, and if cut and punched in England, and riyetted on .ilje Waimea, would then cost little more'than one-third the price of those, pdricr})iSedi f-<The system of xtsing small quantities of water and narrow .boxes is a grea't waste'of labour"and gold. a largo supply of. water is to be found it should be used freely, as the moYe water used, and the wider the boxes, the!

mJBHWH>> the return of gold,.;JTiiiaj .has been proved to the entire satisfaction of the CuUfornian miner*, an! upon toe production of their pUtsttill tiw future ejooeai of the mining'population of Wwt» ?l»tud toe greatextent defend.- XUatftansluicing claim caa be forked to advantage with less than five »ds of water, and this hj not enough here the ground con tains a quantity of very heavy stones. ...The, botes' Jused are never. less than 2ft wide for 6 heads of water; 2ft Gin for 10 heads ; 3ft; Gin for 15 beads; 4ft for 20 heads. These boxes are lined, in the usual way with blocks of yood.ftora 6in to 9in'thick, each 12ft length of box should hive a fall of at least 6in, anything less "'requires an enormous quantity of water. With 12in fall to the 12 ft box a claim is far more valuable. Quicksilver should be used in large quantities, iii order to retain the very fine particles of gold that are sure to escape where a great amount of wash has to pass through. I know hundreds of claims here which produce reasonable returns by being forked in the usual way, with a couple heads of water, part of which is brought through a canvass hose, and the balance allowed to run down the face. Now, if these same claims were to adopt a proper system, I am quite confident the returns, after paying all expenditure, would be increased three-fold. The whole plan is simple.; keep on all possible pressure by using the iron pipes, use larger quantities of water, widen your boxes, use quicksilver, and keep as much fall as possible. If these simple instructions are attended to, ground, thousands of acres that are now considered worthless, will yield handsome returns. The Greenstone and Hohonu Water-race Company will have a claim at work on this principle within a few weeks, so that ail those who are interested in hydraulic sluicing will have an opportunity of see ing the same in full operation. Mr Anderson, the manager, thoroughly understands the details, and will, I am sure, be very glad to give any information oa the subject.