Part 314

Partridge MORTAR, is a common mortar, surrounded by 13 other little mortars, bored round its circumference in the body of its metal. The centre one is loaded with a shell, and the others with grenades. The vent of the large mortar being fired, communicates its fire to the small ones; so that both shell and grenades go off at once. The French used them in the war of 1701, and more especially at the siege of Lisle, in 1708, and at the defence of Bouchain in 1702.

Hand-MORTARS, were frequently used before the invention of cohorns. They were fixed at the end of a staff of 4¹⁄₂ feet long, the other end being shod with iron to stick in the ground: while the bombardier, with one hand, elevated it at pleasure, he with the other hand fired.

Firelock-MORTARS, Bombards, are small mortars, fixed at the end of a firelock they are loaded as all common firelocks are; and the grenade, placed in the mortar at the end of the barrel, is discharged by a flint-lock; and, to prevent the recoil hurting the bombardier, the bombard rests on a kind of halberd, made for that purpose. They were first invented by major-general Siebach, a German, about the year 1710.

Names of the several parts of a MORTAR.

Grand divisions exterior, viz.--The whole length, of the mortar, muzzle, chace, reinforce, breech, trunnions.

Small divisions exterior. The vent, dolphins, vent astragal and fillets, breech ring and ogee, reinforce ring and ogee, reinforce astragal and fillets, muzzle astragal and fillets, muzzle ring and ogee, muzzle moulding, shoulders.

Interior parts. Chamber, bore, mouth, vent.

Chamber in MORTARS, is the place where the powder is lodged. There are different sorts, and made variously by different nations. The Spaniards use chiefly the spheric; the French, Germans, and Dutch, the conic, cylindric, and the concave or bottled; the Portuguese at present, the parabolic; and the English make them in the form of a frustrum of a cone. Each nation has its reasons, good or bad, to prefer their make before that of others: among which the English say the concave and cylindric chambers are the best; the French say the frustrum of a cone.

Sea-MORTARS; are those which are fixed in the bomb-vessels, for bombarding places by sea: they are made somewhat longer, and much heavier than the land-mortars.

Land-MORTAR-BEDS, are made of very solid timber, and placed upon very strong timber frames, fixed in the bomb ketch; to which a pintle is attached in such a manner, that the bed may turn round. The fore part of these beds is an arc of a circle, described from the same centre as the pintle-hole. Land-mortar-beds are now made of cast iron.

Stone-MORTARS, serve to throw stones into the enemy’s works, when near at hand; such as from the town into the trenches in the covert-way, or upon the glacis; and from these trenches into the town. The bore is terminated by two quadrants of a circle, terminated by the reinforce and lines drawn from the ends of the cylinder, made to lodge the tompions parallel to the axis of the mortar. The bottom of the conic chamber is terminated by an arc of 60 degrees, and the round part of the outside is a semi-circle.

Chambers in MORTARS, are of different sorts and dimensions. Mr. Belidor mentions four; namely, the cylindric, the spheric, the conic, and the concave or bottled; to which a fifth may be added, the parabolic, invented by count de Lippe Buckeburg.

Cylindric chambers. Experience demonstrates, that concave chambers will throw the shell farthest of any with the same charge, yet, in this case, where but little powder is required, in the entrance would become too narrow, and consequently inconvenient to clean; whereas, when they are cylindric, the difference between the advantages of the one and the other will be but little, and not attended with any inconveniences.

Conic chambers, are generally made in a circular form at the bottom, so that the sides produced, meet the extremities of the diameter at the mouth.

Spheric chambers, are much inferior to the cylindric or concave; for it is well known by the properties of geometry, that when a cylinder and a frustrum of a cone occupy equal spaces, the surface of the cone is always greater than that of the cylinder. Hence, if the entrance of these chambers be not made very narrow, contrary to practice, as demonstrated by Mr. Muller, in his second edition of Artillery, page 38, of the introduction, and the examples that follow, we conclude that these and the conic chambers are the worst.

Concave chambers. The advantage of these kinds of chambers consist in this, that their entrance may be made narrower than that of any other form; and practice has sufficiently proved it. Yet, when the entrance is so small as not to admit a man’s hand, they are not easily cleaned: for which reason it is supposed that all 13 and 10-inch mortars should have concave chambers, and the others cylindric ones.

Parabolic chambers. These chambers, being the widest of any, may therefore be included among the worst; as it is not the inward figure of the chamber, but its entrance, which produces the effect; because the smaller it is, the nearer it reduces the effect into the direction of the shell. It has however one advantage, namely that the shells will have no windage.

MORTAR, in military architecture, a composition of lime, sand, &c. mixed up with water, that serves as a cement to bind the stones, &c. of any building. Mine sand makes weak mortar, and the rounder the sand, the stronger the mortar; and if the sand is washed before it is mixed, so much the better.

The proportion of lime and sand for making mortar is extremely variable. Some use three parts of pit-sand, and two of river-sand, to one of lime; others, a proportion of sand to quick-lime as 36 to 35. It should be well mixed, and beat every 24 hours for a week together, letting it then lie for a week more; and when it is used, must be beat and mixed again. By this means it will make good mortar, though the lime is but indifferent.

MORTAR for water-courses, cisterns, &c. is made of lime and hog’s lard; sometimes mixed with the juice of figs, and sometimes with liquid pitch, which is first slaked with wine; and, after application, it is washed over with linseed oil.

MORTAR furnaces, &c. is made with red clay wrought in water wherein horse dung and chimney-soot have been steeped; by which a salt is communicated to the water, that binds the clay, and makes it fit to endure the fire. The clay must not be too fat, lest it should be subject to chinks: nor too lean or sandy, lest it should not bind enough.

MORTAR, made of terras, puzolana, tile-dust, or cinders, is mixed and prepared in the same manner as common mortar; only these ingredients are mixed with lime instead of sand in a due proportion, which is to be in equal quantities. As this mortar is to be used in aquatic buildings, the lime should be the very best.

In fortifications, docks, or piers of harbors, lay all the works under water with terras-mortar, and the rest of the facings, both within and without, with cinder or tile-dust mortar, for about two feet deep.

The East India MORTAR for building and plaistering, is made with shell lime, brick dust pulverized, (called soorkee) washed sand, and the raw juice of the sugar cane, (called jaggeree.) The proportions of different kinds of work are different; but well made and mixed, surpasses all others; the roofs of houses, as well as the floors of their chambers, and the walls are covered with this composition, which, skilfully executed, bears a polish and smoothness like marble.

MORTES-Payes, Fr. Soldiers that were paid for the constant duty of a town or fortified place, both in the time of peace and war. Infantry regiments, which were occasionally stationed in citadels and garrisoned towns, took the right of the mortes-payes, and had the precedence in chusing lodgings.

MORTISE, a hole cut in wood, so that another piece may be fitted into it.

MORTS, Fr. The dead on a field of battle are so called.

MOT, Fr. Parole, watchword.--This word bears the same import in French that it does in English. See PAROLE.