Part 389

Cohorn mortars, having a hole ·1 of an inch in depth in the chamber, or ·15 in the chase, are rejected: royal howitzers the same. 8 inch howitzers having a hole ·15 of an inch in depth in the chamber, or ·2 in the chase, will be rejected.

Carronades. The diameter and position of their bore and chamber must not deviate ¹⁄₂₀ of an inch. They are proved with two rounds, with their chambers full of powder and 1 shot and 1 wad. A hole of ²⁄₁₀ of an inch in depth in the bore, or ¹⁄₁₀ in the chamber condemns the piece.

Proof Charges.

-------+--+--+--+--+-- 68 Prs.|42|32|24|18|12 -------+--+--+--+--+-- 13 lbs.| 9| 8| 6| 4| 3 -------+--+--+--+--+--

All ordnance, after having undergone this proof, and the subsequent searching, are subject to the water proof: this is done by means of a forcing pump, having a pipe or hose fixed to the mouth of the piece: after two or three efforts to force the water through any honeycombs or flaws which may be in the bore, they are left to dry; and generally the next day examined by the reflected light from a mirror. If the bore contains any small holes or flaws which have not been discovered by the former proofs, they are very readily found by this; the water will continue to weep, or run from the holes, when the solid parts of the bore are perfectly dry. Ordnance suspected of being bad are often subject to a more severe proof: that of firing 30 rounds quick, with the service charge and a shot; and in doubtful cases, where the purity of the metal is suspected, recourse has been had to chemical trials and analysis. A quantity of clean filings taken from a part of an iron gun free from rust, are dissolved in diluted sulphuric acid, and the quantity of gas disengaged during the solution accurately ascertained. The plumbago which remains after solution is also separated by filtration, and carefully weighed. Now it is well known that the purer the iron, the greater the quantity of inflammable gas obtained, and the less the proportion of plumbago which remains after the solution; from these two parts therefore a tolerable judgment may be formed of the quality of the metal. When the plumbago exceeds 4¹⁄₂ per cent. the iron will always be found deficient in strength; and there has been no instance of a gun bursting where the plumbago did not exceed 3 per cent.; that is, where 100 grains of the metal did not leave more than 3 grains of plumbago. The color of the plumbago is also to be attended to; when it is brown or reddish, it is an indication of hard metal, and when in quantities and mixed with coals, there can be no doubt but that the iron is too soft for cannon.

Proof of Iron Shells. After the shells are guaged and examined as to their dimensions and weight, they must be well scraped out, and the iron pin at the bottom of the inside must be driven down or broken off. They are then to be hammered all over, to knock off the scales, and discover flaws, and no hole, in the large shells is allowed, of more than ³⁄₄ of an inch deep. An empty fuze is then driven into the fuze hole, and the shell is suspended in a tub of water, in such manner that the shell be covered by the water, but that it does not run into the fuze: in this situation the nose of a pair of bellows is put in at the fuze hole, and several strong puffs given with the bellows; and if no bubbles rise in the water, the shell is concluded to be serviceable.

Ordnance condemned as unserviceable for any of the foregoing reasons, are marked as follows: ╳ D, or ╳ S, or ╳ W. The first signifies that they are found to be faulty in their dimensions, by Desagulier’s instrument; the second, by the searcher; and the third, by the water proof.

PROOF of powder, is in order to try its goodness and strength. There have been different inventions proposed and put in practice heretofore, for the proof of powder. See GUNPOWDER, and EPROUVETTE.

PROOF of cannon, is made to ascertain their being well cast, their having no cavities in their metal, and, in a word, their being fit to resist the effort of their charge of powder. In making this proof, the piece is laid upon the ground, supported only by a piece of wood in the middle, of about five or six inches thick, to raise the muzzle a little; and then the piece is fired against a solid butt of earth.

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.

PROPER pivot flank in column, is that which, when wheeled up to, preserves the divisions of the line in the natural order, and to their proper front. The other may be called the reverse flank. In column, divisions cover and dress to the proper pivot flank; to the left when the right is in front; and to the right when the left is in front.

PROPLASM. See MOULD.

PROPORTION, (Proportion, Fr.) The relation which parts have among themselves, and to the whole.

PROPOSER une personne pour une charge, Fr. To recommend a person for a situation.

PROPOSITION, (Proposition, Fr.) in geometry, the declaration of a truth which is proved by demonstration. Such are the propositions in Euclid’s Elements. Propositions are divided into Problems and Theorems.

PROPREFECT, among the Romans, the prefect’s lieutenant, whom he commissioned to do any part of his duty in his place.

PROPRETE des soldats, Fr. Cleanliness required in soldiers. See SERJEANT.

PROPRETOR, the same in his relative capacity as proconsul among the Romans. He was a magistrate who, after having discharged the office of pretor at home, was sent into a province to act in the same capacity.

PROQUESTOR, among the Romans, the questor’s lieutenant, who discharged his office in his stead.