Reducing appliances have often to be placed in districts where the water supply is insufficient for the battery. When this is so every available means must be adopted for saving the precious liquid, such as condensing the exhaust steam from the engine. This may be done by conducting it through a considerable length of ordinary zinc piping, such as is used for carrying the water from house roofs. Also tailings pits should be made, in which the tailings and slimes are allowed to settle, and the cleared water is pumped back to be again used. These pits should, where practicable, be cemented. It is usual, also, to have one or two tailings dams at different levels; the tailings are run into the upper dam, and are allowed to settle; the slimes overflow from it into the lower dam, and are there deposited, while the cleared water is pumped back to the battery. Arrangements are made by which all these reservoirs can be sluiced out when they are filled with accumulated tailings. It is well not to leave the sluicing for too long a period, as when the slimes and tailings are set hard they are difficult to remove. Where a permanent reducing plant is to be erected, whatever form of mill may be adopted, it is better for many reasons to use automatic ore feeders. Of these the best two I have met are the “Tulloch” (Fig. 18), and “Challenge” (Fig. 19) either of which can be adapted to any mill and both do good work. By their use the reducing capacity of the mill is increased, and the feeding being regular the wear and tear is decreased, while by the regulated feeding of the “pulp” in the battery box or mortar can be maintained at any degree of consistency which may be found desirable, and thus the process of amalgamation will be greatly facilitated. The only objection which can be urged against the automatic feeder is that the steel points of picks, gads, drills, and other tools may be allowed to pass into the mortar or mill, and thus cause considerable wear and tear. A remedy for this is suggested (p. 148). [Illustration: PLATE IV.--TAIL RACE _To face p._ 74] [Illustration: FIG. 18. TULLOCH AUTOMATIC ORE FEEDER.] [Illustration: FIG. 19. CHALLENGE AUTOMATIC ORE FEEDER.] If local conditions are favourable and the management good, some mines have paid well with a yield of from 1½ to 4 dwts. of gold per ton of ore; but others have not paid with much higher yields in test crushings. Great judgment is required in selecting the best possible site for the class of crushing machinery decided upon. The crusher should be as high as can be managed so as to give a good clear run for the tailings and room for the concentrators and amalgamators, &c., below the copper plates and blanket strakes. Solid, strong foundations are essential; many failures are due to a neglect of this point.