1. What will be the weight of a hollow ball or shell of cast-iron, the external diameter being 94, and internal diameter 8 inches? Opposite 9 are 118′06, and Opposite 8 are 92.24, subtract 4 25 82 lbs., weight required. 2. Requiring to remove a cast-iron ball 37 8 lbs. in weight, and in diameter 6 inches, and replace it by one of lead of an equal weight, what must be the diameter of the leaden ball? Weight of lead to that of cast-iron = 156, Then 6.59 = /176 5.6 inches, the diameter, TO TRANSFER ENGRAVINGS TO PLASTER CASTS.-Cover the plate with ink, and polish its surface in the usual way; then put a wall of paper round it, and when completed pour in some finely pow dered plaster of Paris mixed in water; jerk the plate repeatedly, to allow the air bubbles to fly upwards, and let it stand one hour; then take the cast off the plate, and a very perfect impression will be the result. TABLE Of the weight of one foot length of Malleable Iron, FRESCO PAINTING.-Apply any colors that are not injured by lime (according to taste), on a fresh mortared or plastered wall. TO TAKE FAC-SIMILES OF SIGNATURES.-Write your name on a piece of paper, and while the ink is wet sprinkle over it some finely powdered gum arabic, then make a rim round it, and pour on it some fusible alloy, in a liquid state. Impressions may be taken from the plates formed in this way, by means of printing ink and the copperplate press. WATCHMAKER'S OIL, WHICH NEVER CORRODES OR THICKENS.-Take olive oil and put it into a bottle, then insert coils of thin sheet lead. Expose it to the sun for a few weeks, and pour off the clear oil. TABLE Of the Dimensions and Weight of Coppers, from 1 to 208 gallons. The Dimensions taken from lag to brim. Weight of Cast-Iron Plates, per superficial foot. From one-eighth of an inch to one inch thick, THE MANNER OF SOLDERING FERRULES FOR TOOL HANDLES, &c.— Take your ferrule, lap round the jointing a small piece of brass wire, then just wet the ferrule, scatter on the joining ground borax, put it on the end of a wire, and hold it in the fire till the brass fuses. It will fill up the joining, and form a perfect solder. may afterwards be turned in the lathe. It CAST ENGRAVINGS.-Take the engraved plate you intend to copy, and arrange a support of suitable materials round it, then pour on it the following alloy in a state of perfect fusion: tin 1 part; lead 64 parts; antimony 12 parts. These "cast plates" may be worked off on a common printing-press, and offer a ready mode of procuring cheap copies of the works of our celebrated artists. |