328 Scientific Proceedings, Royal Dublin Society. 



DESOEIPTION OF PLATES. 

 Plate XXII. 



Figs. 1 and 2. — Represent diagramatically the arrangement of launders 

 (L L') and liutclis (H H^) employed at some of the Ovoca mines. The 



waters entering at (L) flow along the launders (/i 4 4 ~^^) ^'l^^ 



bottoms of which are strewn with fragments of iron, &c. 



When being cleared ovit a movable partition in the side of the hiitch 

 at (a) is taken up and placed across the launder as shewn by the dotted 

 lines, that portion of the launder above this is then brushed down 

 and the metals agitated with a rake, the water and suspended copper 

 passing into the hutch at {a) in which the copper accumulates while 

 the water flows back to the launder at (h). This portion being finished, 

 the same operation is repeated for the next hutch and so on through the 

 whole series. 



When the suspended copper has subsided in the hutch the super- 

 natant water is drawn off" either through a plughole in the side or b}'- a 

 siphon. 



Figs. 3 and 4. — Represent in section and plan the launders used 

 underground in Cronebane. 



The water enters at (A) passes dov/n through the metals and rack 

 (r) (on which the irons are piled) under the movable partition (m) 

 and ascending through the rack (r') (and irons) it passes over the fixed 

 partition (_/') into the next compartment (B) in the direction indicated 

 by the arrows. 



The irons in these launders are agitated with an iron rake once a 

 day when the precipitate falls off" and settles in the space (S) from wlience 

 it is collected once a quarter or oftener if requisite. 



Plate XXIII. 



Fig, 1. — Represents the cross section of a drift in which there are 

 placed an inflowing launder (I), and exit launder (E). Above these 

 is placed the wire tramway (R) supported on iron supports (S) and 

 which carries the small waggon (W). 



Fig. 2. — Is a side view of the waggon with the carriage that supports 

 it on the wire rope. 



Fig. 3. — Is an enlarged end view of the supporting strap (H) showing 

 the wheel in position on the rope (R) the latter being held by a support 

 (S) driven into the side of the level. 



Fig. 4. —Is the form of support that is used to suspend the wire rail 

 from the roof of the level. 



Fig. -5. — The cross section of an adit level where the launder (L) is 

 placed in the centre supported on transverse sleepers (S), the sides being 

 siqjported by the blocks (B) that carry the rails (R). The waggon (W) 

 thus passing above the launders. A channel (C) is left underneath for 

 flood waters, &c. 



