Tools to PROVE cannon are as follow, viz. Searcher, an iron socket with branches, from four to eight in number, bending outward a little, with small points at their ends: to this socket is fixed a wooden handle, from eight to twelve feet long, and 1¹⁄₂ inch in diameter. This searcher is introduced into the gun after each firing, and turned gently round to discover the cavities within: if any are found, they are marked on the outside with chalk; and then the searcher with one point is introduced, about which point a mixture of wax and tallow is put, to take the impression of the holes; and if any are found of ¹⁄₉th of an inch deep, or of any considerable length, the gun is rejected as unserviceable to government.
Reliever, an iron ring fixed to a handle, by means of a socket, so as to be at right angles: it serves to disengage the first searcher, when any of its points are retained in a hole, and cannot otherwise be got out. When guns are rejected by the proof masters, they order them to be marked ╳ which the contractors generally alter to W P, and after such alteration, dispose of them to foreign powers for Woolwich proof.
A most curious instrument for finding the principal defects in pieces of artillery, has been invented by lieutenant general Desaguliers, of the royal regiment of artillery. This instrument, grounded on the truest mechanical principles, is no sooner introduced into the hollow cylinder of the gun, than it discovers its defects, and more particularly that of the piece not being truly bored, which is a very important one, and to which most of the disasters happening to pieces of artillery, are in a great measure to be imputed; for, when a gun is not properly bored, the most expert artillerist will not be able to make a good shot.
Proof of mortars and howitzers, is made to ascertain their being well cast, and of strength to resist the effort of their charge. For this purpose the mortar or howitzer is placed upon the ground, with some part of their trunnions or breech sunk below the surface, and resting on wooden billets, at an elevation of about 70 degrees.
The mirror is generally the only instrument to discover the defects in mortars and howitzers. In order to use it, the sun must shine; the breech must be placed towards the sun, and the glass over against the mouth of the piece: it illuminates the bore and chamber sufficiently to discover the flaws in it.
PROOF armor, armor hardened so as to resist the force of an arrow, a sword or other weapons in use before the discovery of gunpowder.
Proof charge, the quantity of gunpowder which is used in trying the several pieces of ordnance.
PROPER, in military matters, stands as a reduplicative, serving to mark out a thing more expressly and formally, viz.
Proper front of a battalion. The usual continuity of line which is given to the formation of a battalion, and which remains unaltered by the countermarch or wheelings of its divisions; or if altered is restored by the same operation.
Proper right, the right of a battalion, company, or subdivision, when it is drawn up according to its natural formation.