6 | 102 ... 3-3/4| | 31 | 164 ... 6 | 102 ... 3-3/4| | 32 | 164 ... 6 | 102 ... 3-3/4| | 33 | 153 ... 5-1/2| 96 ... 3-1/2| | 34 | 153 ... 5-1/2| 96 ... 3-1/2| | 35 | 153 ... 5-1/2| 96 ... 3-1/2| | 36 | 153 ... 5-1/2| 96 ... 3-1/2| | 37 | 153 ... 5-1/2| 96 ... 3-1/2| | 38 | 142 ... 5-1/4| 89 ... 3-1/4| | 39 | 142 ... 5-1/4| 89 ... 3-1/4| | 40 | 142 ... 5-1/4| 89 ... 3-1/4| | 41 | 131 ... 4-3/4| 82 ... 3 | | 42 | 131 ... 4-3/4| 82 ... 3 | | 43 | 131 ... 4-3/4| 82 ... 3 | | 44 | 131 ... 4-3/4| 82 ... 3 | | 45 | 120 ... 4-1/2| 75 ... 2-3/4| | 46 | 120 ... 4-1/2| 75 ... 2-3/4| | 47 | 120 ... 4-1/2| 75 ... 2-3/4| | 48 | 120 ... 4-1/2| 75 ... 2-3/4| | 49 | 120 ... 4-1/2| 75 ... 2-3/4| | 50 | 120 ... 4-1/2| 75 ... 2-3/4| +------+------------------+------------------+ N.B.--Revolving Arms of the Fifth Class shall be proved once only, and such Proof shall be by the Scale laid down for definitive Proof of the Fourth Class. [Illustration] As soon as a number of gun barrels are loaded according to the foregoing scale, they are taken to a house or detached building, standing apart from other offices. (The woodcut represents the interior accurately.) The house is lined throughout with thick sheet iron, and the windows, which resemble Venetian blinds, are constructed of the same metal. Iron frames are laid the whole length of the room; on these the barrels of various qualities, when about to be fired, are placed. In the front of these frames lies a large mass of sand, to receive the balls. Behind the frame, on which the twist barrels are fixed, lies another bed of sand; in which, on the recoil, the barrels are buried. Behind the frame, on which the common barrels or muskets are tried, a strong iron bar is placed, having a number of holes large enough to receive the tang of the breech, but not the barrel. The barrels being thus fixed, it is impossible for them to fly back. A groove runs along the whole length of each frame, in which the train of powder is strewed to ignite the charges, upon which the barrels are laid, with the touch-holes downwards.