A very useful pump, in regions where transportation is a problem, is the California pump. It is a rough chain-pump. A box 10 inches by 3 inches, inside measurement, and 10 feet to 30 feet in length, according to requirements, forms a tube reaching from the water to be removed to the level at which it is to be discharged. In this an endless band of stout canvas or leather works, passing under a roller at the lower end, which is immersed in the water. At the higher end the belt passes around a drum worked by water, horse, or manual power. On the belt are wooden or metal projections that fit the box, forcing the water upward as the drum revolves. HYDRAULIC DATA. The prospector, and more especially the miner, will do well to commit the following figures to memory: An Imperial gallon of water weighs 10 pounds. Gallons multiplied by .1606 equals cubic feet. Cubic feet multiplied by 6.288 equals gallons. Gallons multiplied by 277.46 equals cubic inches. Cubic inches multiplied by 0.003604 equals gallons. Cubic feet multiplied by 62.8 equals pounds. Pounds multiplied by .0166 equals cubic feet. Gallons multiplied by 0.004464 equals tons. Tons multiplied by 224 equals gallons. Tons multiplied by 35.97 equals cubic feet. A head of 10 feet gives a pressure of about 4-1/3 pounds to the square inch. Let H represent the head of water in feet, and P the pressure to the square inch. Then: H equals P times 2.311. P equals H times .4326. A FIRE LUTE. To make a fire-proof joint between the lid and body of a retort, or crucible, use the following as a lute: Quartz sand. 8 parts. Clay (pure as possible) 2 parts. Horse dung 1 part. Mix and temper like mortar. CONTENTS OF A VEIN. To find the number of cubic feet per fathom of matter in a vein, multiply its thickness in inches by 3. Great care is requisite in estimating the ore in a vein or the amount of mineral in sight. Very clever men often make grave mistakes in such calculations. A MAKE-SHIFT FLUX. Rough smelting may be done with powdered white glass, though either borax or carbonate of soda is better. As soon as the gold is melted and the flux fluid and still, remove the bulk of the flux with an iron spoon, and pour the metal into a clay mould. Crush the flux for gold. SAVING BLAST SAMPLES. Place a quantity of spruce boughs over a hole before firing the shot, and very few stones will fly. A SIMPLE RETORT.