_Iron Guns._—The guns are first examined as to their proper dimensions, in which, in no case more than ³/₁₀ of an inch variation is allowed; and in the diameter of the bore only ¹/₃₀ from 42 to 18 pounders, and ¹/₄₀ from 12 to 4 pounders; but in the position of the bore ½ an inch out of the axis of a piece from a 42 to an 18 Pr. and ⅓ of an inch from a 12 to a 4 Pr. is allowed. They are then fired twice with the charge in the following table, with one shot and two high junk wads; and examined with a searcher after each round. In this examination they must not have any hole or cavity in the bore of ²/₁₀ of an inch in depth, behind the first reinforce ring, or ¼ of an inch in depth before this ring. +---------+--------------+ | Nature. |Proof Charge. | +---------+--------------+ | Prs. | lbs. oz. | | 42 | 25 — | | 32 | 21 8 | | 24 | 18 — | | 18 | 15 — | | 12 | 12 — | | 9 | 9 — | | 6 | 6 — | | 4 | 4 — | | 3 | 3 — | | 2 | 2 — | | 1½ | 1 8 | | 1 | 1 — | +---------+--------------+ Iron guns are scaled with ¹/₁₂ the weight of the shot. _Brass Guns._—From 1 pounders to 12 pounders the diameter of the bore must not vary more than ¹/₁₀ of an inch, and in no dimensions more than ²/₁₀. The following are the established charges for their proof. The heavy and medium guns with a charge equal to the weight of the shot, except the medium 12 pounder, which is proved with only 9 lbs. The light guns with half the weight of the shot. The brass ordnance have not however been proved of late with such heavy charges, but with the following: 3 Prs. light, 3 times, with 1 lb. each round. 6 Prs. light, 3 times, with 2 lbs. each. 12 Prs. light, 2 times, with 4 lbs. each. 12 Prs. Med. 2 times, with 5 lbs. each. Any hole .15 of an inch deep upwards or sideways in the bore, or .1 in the bottom, between the breach and first reinforce; or .2 of an inch upwards or side ways, or .15 in the bottom of the bore, before the first reinforce ring, will be sufficient to condemn them. _Brass Mortars and Howitzers._—The exterior dimensions are in no respect to deviate more than ¹/₁₀ of an inch in an 8 inch howitzer, and ¹/₂₀ in the royals and Coehorn mortars and howitzers. Their bores and chambers not to deviate from their true diameters or positions more than ¹/₄₀ of an inch. The brass mortars and howitzers are fired twice with their chambers full of powder, and an iron shell. The mortars on their own beds, at about 75° elevation; and the howitzers on their carriages, at about 12°. Iron mortars are proved on their iron beds; with a charge equal to the full chamber, and an iron shot equal in diameter to the shell.