The Book of the Sword

by Sir Richard Francis Burton

I now proceed to consider various points connected with the curved and straight forms of blade. The experience of the Sword-cutter has noticed that the shape of any pattern or model, whether of tool or of weapon, suggests its own and only purpose. This is what we should expect. A swordsman chooses his Sword as a sawyer his saw. Show the mechanic a new chisel, and its form at once explains to him its use: he learns by the general shape, the edge-angle, the temper, the weight, and similar considerations, that it is not made to drive nails, nor to bore holes, and that it is intended to cut wood or soft substances. Thus, too, the form of the Sword is determined by the duty expected of it.

The Sword has three main uses, cutting, thrusting, and guarding. If these qualifications could be combined, there would be no difficulty in determining the single best shape. But unfortunately—perhaps I should say fortunately—each requisite interferes to a great extent with the other. Hence the various modifications adopted by different peoples, and hence the successive steps of progress.

THE CENTRE OF PERCUSSION.

The simplest and most effective form of trenchant instrument intended for cutting only is the American broad-axe used by squatters in the backwoods. This revival of the proto-historic celt and headman’s instrument is a plain, heavy wedge of steel, fixed on a light, tough wooden helve or heft, thus concentrating all the force in the head that strikes the blow. Here there is no uncertainty about the use; and, were it not necessary in swordsmanship to ‘recover guard’ and to save self as well as disable the assailant, it would be the best, as it is one of the oldest, weapons derived from the club. But the cutting Sword, which in the short curved form is its congener, has a long blade that allows a choice of cut—a good choice and a bad choice. If the blow be made, for instance, at a tree-branch with the Sword-point (the ‘whole-weak’), its sole effect will be to jar wrist and arm unpleasantly. The same result will follow a blow with the ‘whole-strong.’ In either case the vibration of the blade shows a waste of strength. By the experiment of cutting along the entire length, inch after inch, and by comparing the effect, the swordsman comes at last to a point, about the end of the ‘half-weak,’ speaking roughly, where there is no jar, and where, consequently, the whole force of the blow becomes effective. But our ‘centre of percussion’ must not be confounded with the ‘centre of gravity.’ This balance-position is situated in the middle of the ‘whole-strong,’ the proper part for guarding, and for guarding only.

The late Mr. Henry Wilkinson, of London, a practical man of science, first proposed a formula for determining the centre of percussion without the tedious process of experimenting with each and every blade. His system was based upon the properties of the pendulum. A light rod, exactly 39·2 inches long, capped with a heavy leaden ball, and swung to and fro upon a fixed centre, vibrates seconds or sixty times per minute in the latitude of London, and the three centres of percussion, of oscillation, and of gravity are concentrated within the ball. If it were a mathematical pendulum—a rod without weight—these three points would lie precisely in the core of the ball, or 39·2 inches from the place of suspension. The blade, to be graduated, is suspended, tight-fastened at the point on which it would turn when making a cut, and is converted by swinging into a pendulum. As the length is shorter, so the oscillations are quicker: the blade makes eighty movements to sixty of the pendulum. A simple formula determines the length of such an eighty-vibrations pendulum to be twenty-two inches. This distance, measured from the point at which the blade was suspended, is marked on the back as the centre of percussion, where there is no jar, and where the most effective cut can be delivered.

Fig. 113.—The Infantry ‘Regulation’ Sword.

c.g. Centre of Gravity; c.p. Centre of Percussion.

Again, an examination of the axe shows that the cutting edge lies considerably in advance of the wrist and hand, with the effect of carrying the edge well forward on the ‘line of direction,’ which, in the Sword, passes directly from pommel to point. If the edge were at the back the tendency of the weapon would be to fall away from the line of cut, and this could be overcome only by a certain amount of wasted force. In nearly all curved Swords, except the Japanese, some contrivance is made to give the feeling which we express by ‘the edge leading well forward’; and this point has been carefully studied by nations whose attack is the cut. Usually the line of hilt is thrown forward so as to form an angle with the axis of the blade, and the former is made obtuser or acuter in proportion as the latter is more or less curved. By balancing the weapon upon the pommel the effect becomes evident; the edge falls forward like that of the axe.