HYDRAULIC MINING IN CALIFORNIA.

Westport Times, Volume VIII, Issue 1226, 6 November 1874, Page 2

HYDRAULIC MINING IN CALIFORNIA.

The following paper upon the above subject was read by Mr Patrick Cotniskej, who has recently visited California, before the Hokiuka Institute a few days ;— Gentlemen The subject of obtaining a proper supply of water for working the large tracts of auriferous ground which exist on the Coast, has always heen one in which I luive 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 extensive hydraulic workings which are now in full operation there. The present appears to me to be a most suitable tiu;e for discussion of the best system of hydraulic mining, seeing that several large water-races are now in progress, and I presume, will one day be completed. Having been from the e<»r!i<-s!: settlement ot the Coast and being connected with its progress, and being still interested in its prospects, [ am desirous of placing you in pos?ession of such information as I have been able to gain from the experiences of other places, and without pretending to give yon anv elaborate treatise on subject, I hope that a practical narration of the facts which have come under rny notice, may be the means of assisting in the introduction of a more improved system of working- than has hitherto heen adopted on the Coast. The present system of ground sluicing in this country is so well known to you nil, that it is unnecessary for me to allude to it, and I therefore purpose to pass on to what I consider the improved system. In America the water is brought to boar at the highest possible point over the wash, and in ord.-r 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, is a great waste of power, while the use of canvass hose is little bettor, 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 by 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 pipo will depend upon the quantity of watsr intended for use, and the thickness of tha iron upon tho pressure to be had. The material generally in use is the ordinary malleable sheet iron, such as used here for chimney piping. Tho guage generally used is number 1(3, this is sufficiently strong to bear the first 250 ft pressure. Fourteen guage will bear 300, and ten guago -100, and so on in proportion. The piping is usually made in 12ft lengths, each length to fit into the rest, and so retaining its hold by tho pressure of the water. As a guide to the size of piping for use, I have seen ten heads of water having two hundred feet 1 ressure, pass through a pipe 15in. in

diameter, with sin nozzle doing great execution. In many places Sin 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 Bbould with reasonable care last a life time. Ten inch pipe should cost about 2s 3d per running foot, and 15in from 4s to ss. Iron piping should also be used for fluming and conveying 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. As a rule, the pressure in this country is not very great, owing to the comparative evenness of the ground, consequently pipes made of 10 guage iron would,-in most cases, carry the contents qf,the largest races in New Zealand. lamat a loss to understand why cist iron pipes have been introduced for the Waimea Water Race. In a country like this, where carriage is a serious consideration, an enormous saving might have been made had wrought iron pipes been 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 rivetted on the Waimea, would then cost little more than one-third the price of those already purchased. The system of using small quantities of water and narrow boxes is a great waste of labor and gold. Wherever a large supply of water is to be found it should be used freely, as the more water used, and the wider the boxes, the greater will be the return of gold This has been proved to the entire satisfaction of the Californian miners, and upon the introduction of their plans will the future success of the mining population of the Coast to a great extent depend. They consider no ordinary sluicing claim can be worked to advantage with less than five heads of water, and this not enough where the ground contains a quantity of very heavy stones. The boxes used are never less than 2ft wide for 5 heads of water ; 2ft Gin for 10 heads ; Bft Gin for 13 heads ; and 4ft for 20 heads. These boxes are lined in the usual way with blocks of wood from Gin to 9in thick, each 12ft length of box should have a fall of at least Gin, anything less requires an enormous quantity of water. With 12in fall to the 12ft box a claim is far more valuable. Quicksilver should be used in large quantities, in order to retain the very fine particles which 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 worked in the usual' way, with a couple of 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 threefold. 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. It these simple instructions are attended to, ground, thousands of acres that are now considered worthless, will yield handsome returns.