THE GOVERNMENT QUARTZ-CRUSHING MACHINE.

Otago Daily Times, Issue 3247, 3 July 1872, Page 5

THE GOVERNMENT QUARTZ-CRUSH-ING MACHINE.

TO TIIK KIMTOII.

Sir—-I have waited from day to day expecting Hnm'e remarks U> appear in reference to " our battery " on the reclaimed ground ; and although very unwilling to niKh into print, 1 think Homo comments respecting it are loudly called for.

When it was fintt mooted that the Provincial CoviTiimcnt h;id arranged for the erection of a quartz battery, I, with many others, felt it was a want needed, and a decided step ii: the right direction. 1 anticipated that the machine, under the superintendence of experienced men, such aa the Covenimcnt can aurely command, would have been, although t>niaH, a model in its way, and erected with all the latest improvements, ko that it might become a pattern for up-country reefers) to guide them Hhould they require batteries for their own claims. At least, Ji fully expected to find a Blight improvement upon any that had hitherto been erected in Otago. But what is the result '! I have had many ■years' experience inciuartz mining and crushing in Victoria, but i must Bay I never saw a greater " duller" of a plant. The veriest tyro would see that at a glance. Ah thia is a. public work, ami public properly, I think X nave a perfect right to criticise the affair •on public grounds, and a« I have made a very sweeping assertion, it is but right I uhould point out some of my reasons for believing it to bo a "duffer."

In the first place, for the foundation*, I n'iml that (on anything like a solid foundn"fcion) two logs have been laid down parallel to each other, but at sonic distance apart. lOn these, two more arc placed transversely, ■ then two more acrosa thcKo last, and on these is fixed the box, placed on a spring between two logs—thereby causing an amount of 'vibration which would soon ruin the battery were it otherwise perfect. Then the upright • carrying the imn shaft, instead of being separated from the stamper box (as is always the onso now in tlie beat constructed 'batteries) is fastened to it, ncce«t<nrily fiending the jar of the fall of the stamp-heads to ; the cam shaft and wheels. The wp rights are • made of wood, and the stays of iron, two /materials on which the weather haa so different an i:H\:ct that they never act well to gcthcr. But, ibis is not so material an the •placing of said Htajs, and here this fault ;shows a clear want of practical knowledge and mechanical skill in whoever directed the works ; for it ia well known among practical men that there arc two distinct vibrations in .-a battery at work—-one horizontal and the • other perpendicular. The lirat caused by the cams and shaft, and the other by the fall of the stamp-heads. The two vibrations meet at the cam shaft, above which there is no cause of vibration, consequently all preventatives or stays should be placed as clone to, or just beneath, the shaft, so as to cheek the vibration and the jamming of the toothwheels. But what is the case with the battery on the reclaimed land ? Tho stays . are fixed as f.ir from the cause of vibration as they could possibly be, that is, at tfio very top of the uprights, leaving the wholu fabric to rock ami'swing about as ifc pleases. About the cams and discs I have little to say, except that as they are placed there is loss of leverage, and consequently of power. The Avouden guides, in my opinion, are much too • deep, by which the friction is doubled, causing - a proportionate loss of power. Let the battery be worked at its proper speed, and give the stampers their proper fall, atid wheel after wheel will break as fast as they please, and the whole concern be shaken to pieces. At present, if they get live tons of stone through per we*:k, working twenty-four hour.C they will do wonders. Why the engine should have been placed so far from the battery, necessitating belts and intermediate -shafting, I cannot tell, unless it was to expend about one-fifth of the power of the engine, which I believe it does. But enough of the battery. I must now say a few words upon the much more important matter of tlie gold -saving apparatus used. Since my arrival from Victoria, not long since, I have heard of the great loss of quicksilver from the various batteries in use in the colony, in some -cases the loss amounting to a cwt. during a short period ; whilst in another I was told that one machine lost over a ton weight in less than a year. Nov.", we nil know that where mercury is lost in inich quantities, gold must be lost ict proportion. I have conversed with many shareholders in quartz claims up the country, who all acknowledge that their tables lose silver to a considerable extent, but that it could not be- helped. This reasoning I could not admit, bnt since I have seen the

table in use on the reclaimed ground, I was

only surprised, if their tables were anything .liko it, that they could save silver at all, for it ib without exception the beat constructed for washing away silver and gold that has .come under my notice for some time. The design of tho table is bad, and it has the further disadvantage of being badly sefc. A visitor, while I was there, asked where tho gold was caught ? "Oh !" replied some one connected with the mill, "all over, from the box down, to here," pointing to the end of the blanket table, and he might have added —outside too. If that individual had had any experience in Victoria lately, ho "would have known that ..gold or amalgam ought never to pass the

timt ripple, excepting that which adheres to a piece of quartz or i« contained in the pyrites, 1 notice al»o that they are erecting art. amalgamating barrel and a uhaking table. Tho first is very well, but I can scarcely make oul; what they are going to do with a shaking table—an, apparatus long since discarded in Victoria. If to clean up the stuff from the battery after tho termination of a crushing, a!;! I can say is that it is a very alow and inefficient process, and that a cradle for tho purpose is now mostly used. I have written this letter solely on pnblic grounds, and to place up-country minere on their guard against accepting the Government battery as a model, for should they do to it would be the means of entailing upon them a continual source of expense and loss of time in keeping it in working order, cause a great amount of anxiety to any manager, and take away from him much of the time that (should properly be ''evotod to the*mine itself. There ii» "no doubt in my mind that upon the efficiency or non-efficiency of this Government mill, toy though it be, much depends for.good or bad. Had it worked well, been-well managed, and had the yields from the stone brought to it proved satisfactorily, what might it not have been the means of accomplishing for Duticdin and the Province! If, on the other haisti, it hi an utter failure, what mischief may it not cause by retarding the development of our auriferous reefs for some time to come, and also making capitalists and the public generally chary of venturing in quartz mining investments !—I am, &c, W.J. 27th June.