224 MINING INDFSTEY. 



largest is 4 J feet in diameter, and treats 3,000 pounds of ore at a single 

 charge. It weighs 5,000 pounds. 



Within the past two or three years pans of much larger dimensions, and, 

 consequently, of greater capacity than those formerly used, have been intro- 

 duced in the Washoe district, and have, generally, found great favor among 

 mill-men. Until lately they have been chiefly used in working tailings, to the 

 treatment of which, as well as of low-grade ores, they are especially adapted. 

 It is claimed in their favor that they treat a charge of ore three or four times 

 as large as that of the ordinary pans in the same, or but comparatively little 

 more, time, economizing thereby not only time but labor and power. One 

 large pan requires much less machinery and fewer auxiliary parts, in its ope- 

 ration, than three or four smaller ones, of equal capacity in the aggregate. 

 The attention of the workman is more concentrated, and there is a much 

 smaller loss, proportionately, by wastage of ore, quicksilver, and other mate- 

 rials. While the time allowed for amalgamation is much less in the larger 

 charge than in the smaller one, in proportion to the quantity of ore treated, 

 the results, so far, seem to be nearly or equally as good. These considera- 

 tions are of special importance in the working of low-grade ores, which can 

 only be done profitably on a large scale and at small expense per ton, and in 

 which the loss of a small percentage of the value is comparatively trifling in 

 amount. 



McCone's Pan. — The McCone pan, constructed by Mr. McCone, pro- 

 prietor of the Nevada foundery, at Silver City, is one of this kind. Some 

 of the details of its construction, and the method of setting it up, are shown 

 in the drawings^ on Plate XXII. Figs. 1 and 2 show the pan, as it is mounted 

 on a timber frame-work, and the gearing by which it is set in operation. In 

 Fig. 2 a portion of the pan-rim is removed to show the interior. Fig. 3 shows 

 a vertical section and Fig. 4, a plan of the pan. In the latter a portion of 

 the muUer-plate is shown and another portion is removed, exposing the shoes 

 and dies below. This pan is 5 feet in diameter and 28 inches deep. It is 



^ From drawings recently made and farnisbed to the writer by Mr. Tyrrell, of tlie 

 Nevada Foundery. 



