Various devices have been proposed for shot - making, having for their object the abolition of the tower. One process consists in pouring lead upon a revolving table on which is placed a cylinder of perforated sheet brass. The table is revolved with a velocity of 1000 ft. per minute on the periphery, and the lead is thrown through the perforations on the side, forming round shot, which strike against a linen screen placed to intercept them. A method has also been patented for dropping shot through short distances, but subjecting, them meanwhile to a powerful air - current which cools them. After the shot have reached the bottom of the well, they are at once lifted out by an elevator and thrown upon an inclined drying - table, over which they slide, falling ultimately into a wire - gauze rotating cylinder. Here they are rolled and ground together, and in this way the minute burrs upon them are removed. From the cylinder, another elevator lifts the shot upon a screening - table, which consists of a series of planes arranged at gradually decreasing heights. Between each 2 is an interval.
The shot, being started at the end of the highest plane,, will,, if perfect, roll from one plane to another,, jumping over the intermediate spaces; if imperfect, however, the latter become pitfalls, into which, sooner or later, it tumbles and is carried off into a receptacle, the contents of which go back to the melting - kettle. The good shot, after passing this ordeal, reach the separators. There are usually several tables, each devoted to a different, size of shot and its approximating sizes. This is for convenience in future separating. The. shot are next elevated to the top cylinder of a series, arranged on an incline, Two of these cylinders, are represented in Fig. 147. They are conical in form, inclined, and covered with perforated sheet brass. Each cylinder serves as a sieve for a particular size of shot, retaining that and al lowing all smaller sizes to escape. The shot, as the cylinder revolves, traverses its en-tire length, and then the small ones run out into. the next cylinder below, and thus the sifting goes on until each cylinder has picked out the particular class of shot to which it is adapted.
The sizes, of shot are standard. The smallest is known as "dust," and then comes No. 12, which is 0.05 in. in diameter, 2326 shot going to the ox. The sizes then increase by hundredths of an inch up to 23/100, of which there are 24 shot to the oz.
The shot being now assorted, polishing alone remains to be done. This is accomplished by placing the. shot to gether with graphite (plumbago) in a box, which is rapidly rotated. This imparts the glossy black smoothness demanded by sportsmen. The shot are then weighed, bagged, and are ready for commerce..
Buckshot, which range in size from 22 to 38 hundredths of an inch, are moulded. The moulds represented in Fig. .148 consist of a series of pivoted bars, the. outer pair of which have handles. The upper edges of these bars are hollowed to form the moulds, so that when they are closed together the. opposite, halves of each cavity unite, and it is only necessary to pour the lead into the apertures. The shot are thus at once moulded to the proper size, so that rumbling and polishing only are subsequently required.