this great improvement in the manufacture of gunpowder will either be partially or wholly nullified. In arranging the proper quantity of powder and size of grain for a charge the fact should not be overlooked, that though there may appear to be no powder thrown out unburnt, yet, as the charge is ignited gradually, and the combustion is quick or slow according to the size of the grains, a considerable portion is often burnt outside the barrel without falling; the immense velocity of the flame enveloping the unburnt grains, and setting fire to them even after they have left the muzzle of the piece. Any extra amount of powder, therefore, that may thus be used will add to the force of the recoil, but not to the velocity of the shot, as it adds to the dead weight which the inflamed portion of the powder has to lift.

"As a further practical illustration that great recoil is no test of great velocity, let any man take a three-grooved rifle, having the lands as broad or broader than the grooves, and test its initial velocity and recoil, as before, with a nicely fitting bullet and a proper charge of powder. Let him then place the rifle in the hands of a careful rifle-maker, to have a circular shallow groove run up on each land, exactly parallel to the others. Let him then test the rifle again, and he will find that the velocity of the bullet is now greater and the recoil less, and the rifle, consequently, considerably improved. The intelligent marksman or gun-maker will at once perceive that the result is simply owing to there being less friction; for be it remembered that in the act of expanding, the bullet is also in the act of moving forward, and until it is fully expanded, into the grooves, the pressure and retarding friction is caused by the lands alone, and which, being so broad, must also, to a certain extent, retard the quick expansion of the lead into the grooves. In fact, a portion of that power which should be beneficially employed in expelling the shot is uselessly expended in overcoming friction, causing at the same time more recoil-action and reaction being still, and always, equal."

With every word that bears directly on the subject of recoil in this letter I fully agree, though there are some points which may be disputed, as for instance the opinion

which is expressed adverse to the adoption of relief, a term used by Mr. Boucher for what is commonly called "opening behind." This, however, will be discussed hereafter.

In order to show practically the truth of the opinions held by Mr. Boucher, the results of the gun trial held at Hornsey Wood House on the 4th and 5th of July, 1859, are here appended. It will be necessary to exclude from the list all those guns which were fired with a different charge of powder, and to compare together only those of which all the essential elements were alike. The machine adopted was merely a wooden carriage. (Fig. 8 a b) containing the gun securely fixed in a horizontal posi

tion. This carriage slides backwards and forwards in a frame which is firmly fixed to the ground, and it is attached in front to one of Salter's balances (cd), fitted with a slide which registers exactly the extent to which the index is drawn out by the recoil of the gun. The carriage is carefully padded with Indian rubber to prevent injury to the stock or barrels, which latter are secured by the block (fg). At the trial, the carriage was made to run on wheels, but it is better to construct it as here represented, running freely on metal slides. A thumbscrew (e) in front presses the carriage back till it draws out the index to 10lbs., that being at least the pressure with which the gun is

brought against the shoulder, and many people using as much force as would amount to 25 or 30lbs.

By examining the whole table given elsewhere, it will be seen that the average recoil of the guns of a 12 and 13-bore was 66lbs., and of 14, 15, and 16-bore 644lbs., the highest recoil in Class 1 being 761b., and the lowest 591b. In Class 2 the highest was also 761b., and the lowest 44lb. These results are of great interest, and establish the fact which I have always contended for, that the recoil is not in exact proportion to the shooting force of each gun; for, taking the gun which heads the first class, the two barrels penetrated through 28 and 33 sheets respectively at 40 yards, yet the recoil was less than that of the next, by Mr. Prince, which pierced 28 and 22 sheets, and still less than the third in that class, which penetrated 25 and 28. The same holds good throughout the series, and I think it may be alleged that, granting the truth of the test, the proportion of recoil to shooting power varies considerably, and that the greatest kicker is not necessarily the strongest shooting gun. Another interesting point established by the trial is, that the Joe Manton gun sent by Colonel White is by no means remarkable for its amount of recoil, the average of its two barrels being 3lb. under that of the average of all the guns tested in its class; and, lastly, the breech-loaders are shown to be quite equal in recoil to the average of the muzzleloaders.

Thus, in the first class, the three guns standing highest on the list, and showing nearly as great a power of penetration as any, have respectively three, two, and one degrees below the average of recoil, and exactly in an inverse ratio to their performances.

The want of relation between penetration and recoil is still more remarkable in the second class, in which Mr. O. Smith's gun showed a penetration of 38 and 22, with the two barrels, and a recoil 8 degrees below the average; while one of Mr. Reilly's guns, with a slight diminution of penetration, was thirteen over the average in recoil, and this is still more remarkable with the other two guns. I believe, therefore, it may be asserted, that within certain limits it is possible to obtain an increase of penetration without an increase of recoil.

The amount of recoil which can be pleasantly borne by the shoulder, will vary somewhat with the weight of the gun. Thus, a light one of 6lbs. will show perhaps a recoil, according to the machine, of only 65lbs., yet it will be more unpleasant to shoot than another weighing 8lbs., which recoils 70lbs. according to the same test. According to my experiments, I believe that with guns of the usual weight and bore, that is, from 7lbs. to 74lbs. for 12-bore, and a quarter of a pound less for each diminution of size, the recoil, in order to be pleasantly borne, should not on any account exceed 70lbs. Those who are particular in this matter will prefer to have one showing 10lbs. or even 15lbs. less, but to get the highest degree of penetration, the amount of recoil above fixed must be incurred.

The chief causes of undue recoil, are the disproportion of the projectile to the powder, the excessive quantity of the latter, inordinate opening of the barrel, roughness of the metal, or fouling of the barrel, and lastly, a want of sufficient weight of the whole gun to give vis inertia to resist the force of the explosion. Some of these vary with the state of cleanness in which the gun is, and with the charge with which it is loaded, but the others continue the same under all circumstances.

COMPOSITION OF GUNPOWDER, GUNCOTTON, AND OTHER

EXPLOSIVE MIXTURES USED WITH THE GUN.

In order to force the projectile to its proper destination, two explosive substances only have as yet been usefully applied-namely, gunpowder and guncotton; but there are others which are used merely to procure ignition by percussion in some shape or other, being introduced into small metal capsules denominated percussion caps, or into some similar convenient vehicle such as Lancaster's copper disk.

Gunpowder is composed, in all cases, of three substances -nitre, sulphur, and charcoal-but the proportions adopted by different makers vary to some extent. In a work of this nature, intended for the sportsman only, it is scarcely necessary to enter upon the new chemical combinations which follow the explosion of this potent agent, but it may be men