41. What means are afforded at the sea-board forts for heating shot? Furnaces for this purpose are erected, which hold 60 or more shot. [Sidenote: 98]] 42. What length of time is required to heat them to a red heat? The shot being placed and the furnace cold, it requires one hour and fifteen minutes; but after the furnace is once heated, a 24-pdr. shot is brought to a red heat in twenty-five minutes; the 32-pdr. and 42-pdr. shot require a few minutes longer. 43. Describe grates for heating shot. In siege and other batteries, where there are no furnaces, a grate is used. It consists of four bars 1.75 inches square, three feet long, placed four inches apart on three iron stands, one foot in height. It is placed in an excavation one foot in depth, of the width of the grate, perpendicular at the back and side, open in front, the legs resting on bricks or stones rising about four or five inches from the bottom. A roof is made over it with hoops of flat iron, covered with sods and eighteen inches of earth, having in the back part a chimney six inches square. The shot are placed on the back part of the grate, leaving one-fourth of the front part free; and under and on the front part the wood is put, cut in pieces about fourteen inches long and two inches thick. A thick sod is used as a register, to regulate the draught of the chimney, so that no flame can issue from the front. This grate, which will contain about fifteen 24-pdr. balls, heats them to a red heat in an hour, and will supply three guns. 44. How are wads for firing hot shot made? Of hay; by twisting from the hay a rope of an inch or an inch and a half in diameter, and then commencing at one end, and doubling it up about one calibre in length, twisting it all the time until it becomes nearly large enough, when the rope is wound around the wad perpendicular to its axis, and fastened with a hitch. Or the hay may be rammed in a _form_ of proper calibre, and then bound with spun yarn, and afterwards rammed a second time. [Sidenote: 99]] 45. Have hot shot been almost entirely superseded? Yes, since the adoption of the method of throwing large hollow shot from long pieces. These require but little preparation, can be used at once, and are more terrible in their effects. 46. What are _ring_ or _grommet_ wads, and their use? They consist of a ring of rope yarn, about 0.7 in. thick, with two pieces of strong twine tied across at right angles to each other. The size of the ring is the full diameter of the bore, in order that it may fit tight, and stop the windage. They increase the accuracy of fire, and are to be preferred when the object of the wad is to retain the ball in its place, as in firing at a depression. They stop the windage best when placed behind the ball. They may be attached to the straps, or to the ball by twine, or may be inserted like other wads after the ball. [Sidenote: 100]] 47. How are _junk-wads_ made; and for what are they used?