When blasting the cap of a lode, particularly on rich shutes of gold, the rock is apt to fly, and rich specimens may be thrown far afield and so be lost. A simple way of avoiding this is to procure a quantity of boughs, which tie into loose bundles, placing the leafy parts alternately end for end. Before firing, pile these bundles over the blast and, if care is used, very few stones will fly. The same device may be used in wide shallow shafts. A SIMPLE MODE OF RETORTING SMALL QUANTITIES OF AMALGAM. Clean your amalgam and squeeze it as hard as possible through strong calico or chamois leather. Take a large sound potato, cut off about a quarter from one end and scoop out a hole in the centre about twice as big as the ball of amalgam. Procure a piece of flat iron--an old spade will do as well as anything--insert the amalgam, and, having placed the potato, cut side downwards, thereon, put the plate of iron on the forge, heat up first gently, then stronger, till separation has taken place, when the gold will be found in a bright clean button on the plate and the mercury in fine globules in the potato, from which it can be re-collected by breaking up the partly or wholly cooked tuber under water in an enamelled or ordinary crockery basin. It is as well to place a piece of paper between the iron and the amalgam to prevent adhesion. TO RETORT SMALL QUANTITIES OF MERCURY FOR AMALGAMATING ASSAY TESTS. [Illustration: FIG. 34. SMOKING-PIPE RETORT.] Get two new tobacco pipes similar in shape (Fig. 34), with the biggest bowls and longest stems procurable. Break off the stem of one close to the bowl and fill the hole with well worked clay (some battery slimes make the best luting clay). Set the stemless pipe on end in a clay bed, and fill with amalgam, pass a bit of thin iron or copper wire beneath it, and bend the ends of the wire upwards. Now fit the whole pipe, bowl inverted, on to the under one, luting the edges of both well with clay. Twist the wire over the top with a pair of nippers till the two bowls are fitted closely together, and you have a retort that will stand any heat necessary to thoroughly distil mercury. A SIMPLE MODE OF ASCERTAINING THE NOMINAL HORSE-POWER OF AN ENGINE. Multiply the internal diameter of the cylinder by itself and strike off the last figure of the quotient. The diameter is 20” × 20” 20 ----- 40ø. The H.P. is 40. The following rules will be found more professionally accurate from an engineering standpoint, though the term “horse-power” is not now generally employed. _To find the Nominal Horse-power._--For _non-condensing_ engines: Multiply the square of the diameter of the cylinder in inches by 7 and divide the product by 80. For _condensing_ engines: Multiply the square of the diameter of the cylinder in inches by 7 and divide the product by 200.