Part 348

Tirer une PARALLELE, Fr. verbatim, to draw a parallel. To make a direct communication between one trench and another.

PARALLELISM, the situation or quality whereby any thing is denominated parallel.

PARALLELISM of a march. In order to preserve the parallelism of a march in the movement of troops each battalion must be kept perpendicular to the direction it marches upon, the whole of the several battalions in one straight line, and their several marching directions parallel to each other. The first battalion or line becomes the regulating one, and must be regarded as infallible; and from the moment that its direction is ascertained, the commander of each other, and their directing serjeants, are to consider their movements as subordinate to it, and to conform accordingly. It is the helm which guides the line, and must not change cadence; nor will it increase or diminish its speed, but from unavoidable necessity, and by particular order.

The instant communication of the word march is particularly important, that the advanced guides of the whole may step off together, and thereby maintain their line parallel to the one they quitted, and which becomes the principal guide for their battalions; each preserves its six paces from its advanced guide; this distance is to be kept by, and depends on, the replacing officer next to the color, who covers the directing guide; and if these trained guides do step equally, and in parallel directions to each other, they must be dressed themselves in line, and of consequence the centres of their following battalions.

PARALLELISM and distance to be observed in the formation and movement of any considerable body of troops. It is laid down as a general maxim, that no considerable body should ever be formed without a proportion of it being placed in reserve or in second line, and more or less according to circumstances. The movements of such second line will always correspond with those of the first, and it will always preserve its parallelism and distance.

If the first line makes a flank or central change of position, the second must make a change also on such point as will bring it into its relative situation.

The march of the second line in front, is regulated by its own division or battalion of direction, which moves relatively to that of the first line. In forming in line it will march upon its own points which are parallel to, and ascertained in consequence of those of the first.

When the lines break into columns to the front, the second will generally follow those of the first. When the march is to the flanks, the second line will compose a separate column, or columns. When the march is to the rear, the second line will lead in columns.

The distance betwixt the lines, may be in general supposed equal to the front of one or two battalions, and an interval.

The second lines are seldom composed of as many battalions as the first: they are often divided into distinct bodies, covering separate parts of the first line, and consequently preserving a relative parallelism and distance.

Second lines should not always remain extended, they may often be formed in column of battalions, or of greater numbers, ready to be moved to any point where their assistance is necessary.

Whenever the first line breaks, and manœuvres by its right to face to the left, or by its left to face to the right: the movements of the second line are free and unembarrassed, and it may turn round the manœuvring flank of the first line, and take its new position behind it, by extending itself parallel to that direction, how oblique soever it may be.

The central movement generally required from the second line to conform to that of the first, is equivalent to that line marching in two columns of platoons, from near the centre obliquely to the front, and from that situation forming to both flanks.

The movements of the central columns being well understood, those of the battalions of the wings, are similar in two lines.

The officer commanding the second line, must always be properly informed of the nature of the change to be made by the first, that he may readily determine his corresponding movements.

It requires much attention to conduct heads of battalion columns of both lines nearly parallel to their lateral ones, and perpendicularly, or diagonally to front or rear, according to the nature of the movement. To determine with precision, and in due time, their points in the new line, that wavering and uncertainty of march may be avoided. In great movements to allow the soldier every facility of motion without increasing the distances of divisions, and to require the most exact attention on entering the new line, and in forming. To avoid obstacles in the course of marching, but as soon as possible to re-enter the proper path of the column, while out of that path, the colors of that battalion column may be lowered, (as a mark for the neighboring column, not to be then entirely regulated by it) and again advanced when it regains its proper situation.

All the battalions of a second line, must at the completion of every change of position, find themselves placed in the same relative situation with respect to the first, as they were in before the commencement of the movement.

All changes of position of a first line are made according to one of the modes already prescribed: in general, in critical situations, they are made on a fixed flank, or central point, and by the echellon march of platoons or echellons of smaller sections than platoons, where ground and other circumstances require it; and the echellons may upon occasion be each marched in file, but keeping its position: but the movements of a second line being protected, more complicated, and embracing more ground, are made by the march of battalion columns regulated by a certain determined division of the line.

In all cases where a change of position is made on a flank or central point of the first line, the movement of its corresponding point of the second line determines the new relative situation of that second line.

Movements PARALLEL with a line of fire. Movements are said to be parallel with a line of fire, when one or more lines march either in the rear of troops engaged with an enemy, or in face of an enemy, who is advancing to attack. The greatest accuracy and order are required on both occasions, particularly on the latter; for if the second line, which is the line of support, does not preserve its perpendicular direction with respect to every leading point, and its relative parallelism and distance with the line engaged, according to circumstances, it will not only run the risk of becoming useless itself, but will in all probability endanger the line it covers, should any sudden necessity occur for a change of position.

PARALLELOGRAM, (Parallelogramme, Fr.) a plain figure bounded by four right lines, whereof the opposite are parallel one to the other. It likewise means an instrument composed of five rulers of brass or wood, with sliding sockets, to be set to any proportion, for the enlarging or diminishing any map or draught.

PARALYSER, Fr. To paralyse. A term frequently used by the French since the revolution, to express the bad effects of a factious spirit, &c. Un seul factieux quelque fois paralyse toute une administration: one factious man will sometimes render the designs of a whole administration abortive.

PARAMETER. See GUNNERY and PROJECTILES.

PARAPET, in fortification, an elevation of earth, designed for covering the soldiers from the enemy’s cannon, or small shot; its thickness is from 18 to 20 feet; its height 6 on the inside, and 4 or 5 on that side next the country: it is raised on the rampart, and has a slope called the superior talus, or glacis of the parapets, on which the troops lay their arms to fire over. The slope renders it easy for the soldiers to fire into the ditch. It has a banquette or two on the inside for the troops who defend it, to mount upon, for better discovering the country, the ditch, and counterscarp, to fire as they find occasion.

PARAPET of the covert-way, is what covers that way from the sight of the enemy; which renders it the most dangerous place for the besiegers, because of the neighborhood of the faces, flanks, and curtains of the place.

PARAPETS en forme de crémaillere, Fr. Parapets which are so constructed within, in the form of a saw, that one of the faces of the redans, or teeth, is perpendicular and the other parallel to the capital. The chevalier Clariac, in his Ingénieur de Campagne, has given a particular account of these parapets. But the merit of having invented them does not entirely rest with him, since the Marquis de la Fond, director of the fortified places upon the coast of French Flanders, and M. de Verville, chief engineer at Rocroi, have likewise mentioned them.

PARASANG, (Parasange, Fr.) an ancient Persian measure, being usually thirty, sometimes forty, and sometimes fifty stadia or furlongs.

PARC d’artillerie, Fr. See PARK OF ARTILLERY.