MORTAR (continued)

Plates VI and VII

Plate VI. fig. 9. represents the elevation of the. bed of a 10 inch sea mortar; fig.10 is the plan, and II. the front view thereof; fig. 12. exhibits the plan, and fig. 13. the elevation of the bed-bolster.

We have already observed, that the shell is a great hollow ball, charged with powder. Fig. 16. is a perspective view of it, and fig. 17. a section of it, whereby the thickness is exhibited. The parts a and b of the shell are its handles, by which it is lifted up or removed ; and c is the fusehole, or aperture, through which the powder is poured in to charge it.

It appears, by fig. 17. that the lower part of the shell is thickest, by which it becomes heavier on that side, and accordingly falls thereon, and never on the fuse. It is also the better enabled thereby to resist the impression of the powder, by which it is discharged from the mortar. Both of these reasons, however, Mr. Muller conceives to be immaterial, because nothing but an absolute stoppage of the air can exhaust the fuses, as their composition enables them to burn in water, as well as air or earth ; and the explosion of the mortar would not, in his opinion, he able to break them, if they are equally thick every where. The most proper quantity of powder to charge a shell is probably two thirds of the weight which would fill the cavity.

The fuse of it is represented by c d, fig. 17. This is generally a conical tube, formed of beech, willow, or some dry wood, and filled with a compotition of sulphur, salt-petre, and mealed-powder. The shell being charged, .this fuse is inserted in the cavity through the fuse-hole; and, when fired, communicates the fire to the powder in the shell.

The fuses are charged with great care, that nothing may prevent them from communicating the fire to the powder in. the center of the bomb. They are driven into it so as that only about an inch and a half comes out beyond the fuse hole; and then the shell is said to be fixed.

These fuses are also charged long before there is occasion to use them; and that the composition with which they are filled may not fall out, or be damaged by growing damp, the two ends are covered with a composition of tallow, mixed either with pitch or bees wax. When the fuse is to be put into the shell, the little end is opened or cut off; but the great end is never opened till the mortar is to be fired [Le Blod's Elements of War].

When the proper quantity of powder, necessary to charge the mortar, is put into the chamber, it is covered with a wad, well beat down with the rammer. After this the fixed shell is placed upon the wad, as near the middle of the mortar as possible, with the fuse-hole uppermost, and another wad pressed down close upon it, so as to keep the shell firm in its position. The officer then points the mortar, or gives it the inclination necessary to throw the shell to the place designed. When the mortar is thus fixed, the fuse is opened; the priming-iron is also thrust into the touch-hole of the mortar to clear it, after which it is primed with the finest powder. This done, two of the matrosses, or sailors, taking each one of the matches, the first lights the fuse, and the other fires the mortar. The shell thrown out by the explosion of the powder, is thrown to the place intended; and the fuse, which ought to be exhausted at the instant of the shell's falling, inflames the powder contained therein, and bursts it into splinters; which, flying off circularly, occasion incredible mischief wheresoever they reach.

Reference Works