chink and flaw are of much greater importance than the crack, as the effort of the powder is exerted upon the circumference, and not upon the length of the barrel. In a sword or bow, the very reverse of this takes place; for if a crack, though but of a slight depth, occur in either, it will break at that place when bent but a very little; because the effort is made upon the fibres disposed longitudinally; whereas, if the fault be a chink or even a slight flaw, the sword or bow will not give way. The flaw is much more frequent than the chink; the latter scarcely ever occurring but in barrels forged as above, in which the fibres of the metal run longitudinally; and then only when the iron is of an inferior quality. When external and superficial, they are all defects in point of neatness only; but, when situated within the barrel, they are of a material disadvantage, by affording a lodgment to moisture and foulness that corrode the iron, and thus continually enlarge the excavation until the barrel bursts, or becomes dangerous

to use.

one.

the iron.

than the barrel; one end being made to fit the socket of the crank, and the other being furnished with a cylindrical plug of tempered steel, about an inch and a half in length, and having its surface cut in the manner of a perpetual screw, the threads being flat, about a quarter of an inch in breadth, and running with very little obliquity. This form gives the bit a very strong hold of the metal; and the threads, being sharp at the edges, scoop out and remove every roughness and inequality from the inside of the barrel, and render the cavity smooth and equal throughout. A number of bits, each a little larger than the preceding one, are afterwards successively passed through the barrel in the same way, until it has acquired the intended caliber. The equality of the bore is so essential to the excellence of a piece, that the greatest accuracy in every other particular will not compensate for the want of it. Any person who wishes to know the merit of his piece in this respect, may do it with tolerable accuracy, by means of a plug of lead, cast on a rod of iron or wood; or even by a musket ball, filed so as to fit the bore exactly, and pushed through the barrel by the ram-rod, care being taken not to use an iron ram-rod, or much force, lest the ball be fiattened, and an artificial difficulty created.

The barrel may be now considered as quite finished with regard to its inside: at least it has nothing more to be done to it by the maker. The gunsmiths, however, generally make it undergo a further operation of polishing; after which it is in a condition to receive its proper form and proportions externally, by means of the file. To do this with accuracy, four flat sides or faces are first formed then eight, then sixteen, and so on, until it is made quite round; except the reinforc ed part, which in most of the modern work is left forced part is certainly more elegant than the with eight sides. This octagonal form of the rein. round one formerly in use: but it adds to the weight of the barrel without increasing its strength; for the effort of the powder will always ference, without any regard to those places that be sustained by the thinnest part of the circum

are thicker than the rest.

It is absolutely necessary to the soundness of a barrel, that it should be of an equal thickness on every side; or, in the language of the workmen, a barrel ought to be perfectly upright. In order to arrive, as nearly as possible, to this perfect which they call a compass. It consists of an iron equality, the gunsmiths employ an instrument rod bent so as to form two parallel branches about an inch distant from each other. One of these branches is introduced into the barrel, and kept closely applied to the side by means of one other branch descends parallel to this, on the outor more springs with which it is furnished: the side, and has several screws passing through it with their points directed to the barrel. By screwing these until their points touch the surface of the barrel, and then turning the instru ment round within the bore, it is seen where the metal is too thick, and how much it must be reduced in order to render every part of the barrel perfectly equal throughout its circumference. To form the screw in the breech-end of the barrel, the first tool employed is a plug of tempered steel, somewhat conical, and having upon its surface the threads of a male screw. This tool, which is termed a screw-tap, being introduced into the barrel, it is turned from left to right, and back

again, until it has marked out the three or four first threads of the screw: another less conical tap is then introduced; and when this has carried on the impression of the screw as far as it is intended to go, a third tap is employed, which is nearly cylindrical, and scarcely differs from the plug of the breech which is intended to fill the screw thus formed in the barrel. The breechplug has its screw formed by means of a screwplate made of tempered steel, and has several female screws corresponding with the taps employed to form that in the barrel. A plug of seven or eight threads is sufficiently long; and the threads ought to be neat and sharp, so as to fill completely the turns made in the barrel by the tap. The breech-plug is afterwards case-hardened, or has its surface converted into steel, by being covered over with shavings of horn, or pairings of horse-hoof, and kept red-hot in the fire for some time, after which it is plunged into

water.

The last operation is that of colouring the barrel, previous to which it is polished with fine emery and oil, until it presents to the eye, throughout its whole length, and in whatever direction we observe it, a perfectly smooth, equal, and splendid surface. Formerly barrels were coloured by exposing them to a degree of heat which produced an elegant blue tinge; but, as this effect arises from a degree of calcination taking place upon the surface of the metal, the inside of the barrel always suffered by undergoing the same change. This, therefore, added to the painful sensation excited in the eye by looking along a barrel so coloured, has caused the practice of blueing to be disused for some time past. Instead of it, barrels are now browned, as it is termed. To do this, the barrel is rubbed over with aquafortis, or spirits of salt, diluted with water, and laid by until a complete coat of rust is formed upon it; a little oil is then applied; and the surface, being rubbed dry, is polished by means of a hard brush and bees-wax.

When the barrels intended for a double-barrelled piece are dressed to their proper thickness, which is generally less than for single barrels,each of them is filed flat on the side where it is to join the other, so that they may fit close together. Two corresponding notches are then made at the muzzle and breech of each barrel; and into these are fitted two small pieces of iron, to hold them more strongly together. The barrels being united by tinning the parts where they touch, the ribs are fitted in, and made fast by the same means. These ribs are the triangular pieces of iron which are placed between the barrels, running on the upper and under sides their whole length, and serving to hold them more firmly together. The under rib is a late improvement, and is found more effectually to prevent the barrels from warping. When the barrels are thus joined, they are polished and coloured in the manner already decribed.

The twisted barrels are deservedly celebrated for their superior elegance and strength, as well as for the accuracy with which they throw either ball or shot. The iron employed in them is formed of stubs, which are old horse shoe nails procured from country farriers, and from poor people who gain a subsistence by picking them up on the great roads leading to the metropolis. These are originally formed from the softest and toughest iron that can be had; and this is still farther purified by the numerous heatings and hammerings it has undergone in being reduced

from a bar into the size and form of nails. They cost about ten shillings the hundred weight, and twenty-eight pounds are required to make a single barrel of the ordinary size. A hoop of iron, about an inch broad, and six or seven inches diameter, is placed perpendicularly; and the stubs, previously freed from dirt by washing, are neatly piled in it, with their heads outermost on each side, until the hoop is quite filled and wedged tight with them; the whole resembling a rough circular cake of iron. This is put into the fire until it has acquired a white heat; when it is hammered, either by the strength of the arm, or by the force of machinery, until it coalesces, and becomes one solid mass of iron: the hoop is then removed, and the heatings and hammerings repeated, until the iron, by being thus wrought and kneaded, is freed from every impurity, and rendered very tougla and close in the grain: the workman then proceeds to draw it out into pieces of about twentyfour inches in length, half an inch or more in breadth, and half an inch in thickness.

These pieces, however, are not all of the same thickness, some being more and others less than what we have mentioned, according to the proposed thickness of the barrel, and that part of it which the piece is intended to form. One of these pieces, being heated red-hot for five or six inches, is turned like a corkscrew, without any other tools than the anvil and hammer. The remaining portions are successively treated in the same manher, until the whole piece is turned into a spiral, forming a tube whose diameter corresponds with that of the intended barrel. Four of these are generally sufficient to form a barrel of the ordinary length, which is from thirty-two to thirtyeight inches; and the two which form the breech, or reinforced part, are considerably thicker than those which constitute the fore-part, or muzzle of the barrel. The workman first welds one of these tubes to a part of an old barrel, which serves as a handle. Ile then proceeds to unite the turns of the spiral to each other, by heating the tube two or three inches at a time, to a bright white heat, and striking the end of it several times against the anvil in a horizontal direction, and with considerable force: this is termed jumping by the barrel; and the heats given for the purpose are called jun.ping heats. A mandril is then introduced into the cavity; and the heated portion is hammered lightly, to flatten the ridges or burs raised by the jumping at the place where the spirals are joined. As soon as one piece is jumped its whole length, another is welded to it, and treated in the same manner, until the four pieces are united; when the part of the old barrel, being no longer necessary, is cut off. The welding the turns of the spiral is performed exactly in the same manner as before described, and is repeated three times. The barrel is afterwards finished in the same way as a common one. Stub-iron is also wrought into plain barrels; which, as they require a great deal less labour, are only half the price of the twisted ones.

The canons à rubans, or ribbon-barrels, of the French, very much resemble the English twisted barrels. The process pursued in their formation is considerably more operose than that just described, but seems to be far from possessing any advantage over it. The acknowledged superiority of twisted and ribbon barrels over plain ones has induced some persons to counterfeit them, by colouring plain barrels so as to shew a spirai line running from one end to the other. This is done by winding a thread or string in a spiral direction

round a plain barrel, and then wetting the string with the diluted aqua-tortis, or spirit of salt, so that a coat of rust may be formed where the string touches: when the acid is applied the second time over the whole barrel, the part over which the string was applied, by being more rusted than the rest, shows a dark line winding round the barrel, and renders it, when finished, scarcely distinguishable from a twisted or ribbon-barrel, Other barrels are, by the same means, clouded in an irregular manner, so as to resemble those formed of stub-iron. To prove whether or not a barrel is really what it appears to be, we need only fix upon any part on the under side that is covered by the stock, and having cleared it, if necessary, with a fine file, apply a feather dipped in aqua-fortis, which in a little time will render the fibres of the metal distinctly visible, in whatever direction they run.

The Spanish barrels have always been held in great esteem, as well on account of the quality of the iron, which is generally considered as the best in Europe, as because they possess the reputation of being forged and bored more perfectly than any others. It should be observed, however, that of the Spanish barrels, those only that are made in the capital are accounted truly valuable; in consequence of which a great many have been made at other places, especially at Catalonia, in Biscay, with the names and marks of the Madrid gunsmiths; they are also counterfeited at Liege, Prague, Munich, &c. and a person must be a very good judge not to be deceived by these spurious

barrels.

Proofs of barrels.These differ in different countries. The Spanish proof is a very severe one; but, as it is made before the barrel is filed, it is not satisfactory. At the royal manufactories of St. Etienne and Charleville, in France, there were inspectors appointed to see that no barrels were sent out of these places, whether for the king's use or for public sale, without being proved. The first proof was made with a ball exactly fit ting the caliber, and an ounce of powder. The second was made with the same sized ball and half an ounce of powder. The reason given for the second proof is, that the first may have strained the barrel so much, though the injury be not visible, that it will not bear a second trial with a smaller charge; and it is said there really are some of these barrels which stand the first proof, and yet give way in the second.

The usual proof of the Paris barrels is a double charge of powder and shot; that is, two or two and a half drams of powder, and two or two and a half ounces of shot. The English Tower proof, and that of the Whitechapel company, incorporated by charter for proving of arms, are made with a ball of the caliber and a charge of powder equal in weight to this ball: the proof is the same for every size and species of barrel, and not repeated.

Some gunsmiths pique themselves upon making their barrels undergo a second proof; but it is proper to observe, that if a barrel bears any as signed proof, it will sustain the same immediately after, with greater safety than it did at first, as the metal, from being warmed by the first fire, expands more readily to the force of the second explosion.

Mons. de Marolles, speaking of the proofs of barrels, says, "A stronger proof than ordinary might be made by ramming down at top of the powder six or seven inches of dry clay, in place ut a double charge of lead. This is sometimes

employed in proving pieces of ordnance, where, instead of the bullet, two feet of clay is placed over the powder, by which the whole force of the explosion is exerted upon the piece." We entirely agree with the ingenious author of La Chasse au Fusil, in the opinion that the proof he mentions would be much stronger than that which is usually employed; so much stronger, indeed, that we do not believe any barrel could withstand it, unless the clay were put down in the loosest manner possible. The hardest rocks are burst asunder by means of dry clay strongly rammed over the powder that is placed at the bottom of a cylindrical cavity made in them; and we certainly cannot expect that a force sufficient to rend in pieces immense blocks of granite can be resisted by the comparative trifling strength and thickness of a gun-barrel.

Causes of bursting-lt may be safely asserted, that a good barrel very seldom bursts, unless it be charged too highly, or in an improper manner. Whenever, for example, from the bail not being rammed home, a space is left between it and the powder, there is a great risk of the barrel bursting on being discharged. We say a great risk, because, even under these circumstances, it frequently happens that the barrel does not burst. If the ball stops near to the powder, a very small windage is sufficient to prevent this accident; and it is very rare that the ball touches the barrel in every part of its circumference, unless it has been driven in by force with an iron ram-rod; in which case it moulds itself to the cavity, and blocks it up completely. Should this happen, the barrel, however strong it is, will burst, even when the space between the ball and the powder is but very inconsiderable; and the greater the space that intervenes, the more certainly will this event take place. Mr. Robins, when speaking of this matter, says, moderate charge of powder, when it has expanded itself through the vacant space and reaches the ball, will, by the velocity each part has acquired, accumulate itself behind the ball, and will thereby be condensed prodigiously; whence, if the barrel' be not of an extraordinary strength in that part, it must infallibly burst. The truth of this I have experienced in a very good Tower musquet, forged of very tough iron; for, charging it with twelve pennyweights of powder, and placing the ball (loosely) sixteen inches from the breech; on the firing of it, the part of the barrel just behind the bullet was swelled out to double its diameter, like a blown bladder, and two large pieces of two inches long were blown out of it."

A

The same accident will often take place from the mouth of the piece being filled with earth or snow, as sometimes happens when we are leaping a ditch, with the muzzle of the piece pointed forwards; and if in such cases the barrel do not burst, it is because these foreign bodies stop it up but very loosely. For the same reason, a barrel will certainly burst, if fired when the muzzle is thrust into water but a very little depth below the surface; the resistance given to the passage of the inflamed powder through the mouth of the piece being, in this case, much greater than that afforded by the sides of the barrel. Except in the circumstances mentioned, or in case of an overcharge, it is very rare that a barrel bursts. Whenever it happens independent of these, it is from a defect in the work, and that either the barrel has been imperfectly welded, or that a deep flaw has taken place in some part of it; or, lastly, that through want of care in the boring or filing, it is

left of unequal thickness in its sides. The last defect is the most common, especially in low-priced barrels; and, as pieces more frequently burst from it than from the other defects, it ought to be particularly guarded against. The elastic fluid which is set loose by the inflammation of the powder, and which endeavours to expand itself equally in every direction, being repelled by the stronger parts, acts with additional force against the weaker ones, and frequently bursts its way through them; which would not have been the case, had the sides been of the same thickness and strength, and not afforded an unequal repercussion. The weakness of any part of the barrel, occasioned by the inequality of the caliber, will still more certainly be the cause of bursting than that produced by the filing; because the inflamed fluid being suddenly expanded at the wider part, must suffer a compression before it can pass onward, and the whole force is then exerted against the weak place; for gunpowder acts in the radii of a circle, and exerts the same force on every part of the circumference of the circle.

The conclusion to be drawn from all this is, that a thin and light barrel, which is perfectly upright, that is, of equal thickness in every part of its circumference, is much less liable to burst than one which is considerably thicker and heavier, but which, from being badly filed or bored, is left of unequal strength in its sides.

In all that we have hitherto said upon the causes of bursting, the bad quality of the iron has not been taken into account: and we do not know any means of guarding against these defects, whether arising from the badness of metal, or the insufficiency of workmanship, except by purchasing from a gunsmith of established reputation, and giving a good price for the piece. But by this we do not mean to sanction the practice of many of the gunsmiths in the fashion of the day; we are confident in our opinion, that most of their barrels are made too thin; and it may fairly be doubted, whether they have at all improved the quality of the metal. In some experiments made with a barrel of the celebrated Lazaro Cominazzo, and which was five feet ten inches in length, and extremely thin, particularly towards the muzzle, it was observed, that the barrel vibrated so much after the explosion of this charge, as to produce a whizzing or ringing sound that might be heard to a considerable distance from the barrel. And yet this piece, notwithstanding its extreme thinness, was fired with very high charges. The iron appeared to be of an extraordinary fine quality; which goes to prove that the cohesion of the particless of the metal is the force which resists that of the powder; and hence great advantage might be drawn to the manufacture of barrels, from an accurate knowledge of the force of powder, and the velocity of the ball. For, these points being once determined, it might be known how strong the barrel should be; by which all unnecessary waste of metal might be spared on the one hand, and all danger avoided on the other. For a force equal to that which impels the ball is exerted on the inside of the piece; and if the barrel has not sufficient strength to resist this force, it must of necessity burst.

Of the recoil. The most frequent cause of excess in the recoil is the bore of the piece being wider at one place than another; for although this inequality be so small as to be imperceptible to the eye, the repulse which the expanding flame meets with when passing from the wider to the nar

rower part, renders the recoil much greater than it would have been had the bore been perfectly cylindrical. It is an invariable law in mechanics, that action and re-action are equal; it follows, therefore, that, the weight of the piece being the same, the recoil will be in proportion to the weight of the piece; or, the lighter the piece, the greater the recoil.

In plainer language, the impelling force of the gunpowder is the first and most simple cause of the fire-arms recoiling; for this force acts equally on the breech of the piece and on the ball: so that, if the piece and ball were of equal weight, and other circumstances the same, the piece would recoil with the same velocity as that with which the ball issues out of the piece.

For the same reason, whatever retards the exit of the charge operates like an increase of lead, and by confining the force of the explosion the more to the barrel, produces a greater recoil: hence partly it is, that in proportion as the barrel becomes foul within by repeated firing, the recoil increases. A piece will recoil, if, from the breechplug being made too short, there remain some turns of the screw not filled up, these hollows, wherein a part of the powder is lodged, forming an obstacle that confines and retards the explo sion. A barrel mounted on a stock that is very straight will recoil more than when mounted on a stock that is considerably bent, as the curvature seems to break and deaden the force of the recoil; and sometimes also a fowling-piece will recoil from the shooter applying it improperly to his shoulder; for if the but is not applied closely to the shoulder, or is applied so as to be supported only at a single point, the recoil will be much more sensibly felt than when the hollow of the but embraces the shoulder, and is firmly supported by the weight of the body. Guns are observed to recoil more after being fired a number of times than they did at the beginning. The matter which is left upon the inside of the barrel after the explosion, and which increases on every discharge, attracts moisture very quickly; especially if the saltpetre employed in the powder was not well purified from the admixtures of common salt, which it contains in its rough state. This moisture becomes considerable after a few discharges, and, being formed into vapour by the heat during the explosion, adds its expansive effort to that of the inflamed powder, and greatly increases the agitation and recoil. Owing to this cause, probably, rather than to that before-mentioned, arises the recoil from some turns of the breech-screw not being filled up by the breechplug, and thereby affording a lodgment to mois

ture.

Among the variety of causes to which the excessive recoil of pieces has been attributed, there is one which yet remains to be considered; this is, the touch-hole's being placed at some distance from the breech plug, so that the powder, instead of being fired at its base, is fired near the centre of its charge; whence, it is said, the recoil is increased, and the force of the discharge weakened, by the effort of the powder being exerted more upon the breech than upon the ball or shot. With this idea in view, some gunsmiths form a channel or groove in the breech-plug, as deep as the second or third turn of the screw; the touchhole opens into this channel, and the powder is therefore fired at its very lowest part; and this, they assert, increases the inflammation and the force of the powder. That the distance of the touch-hole from the breech, however, has very

Ettle if any share in the increase of the recoil, we shall prove in the most satisfactory manner, from experiments made purposely to determine this matter. As to the idea that the force of the discharge is diminished by the increase of the recoil, it is too absurd to require discussion: the force exerted by the powder upon the breech is always equal to that which it exerts upon the ball or shot; so that, if there be nothing in the barrel that retards the exit of the ball, an increase in the recoil will be always attended with an increase in the force of the discharge.

The following experiments were made by Mons. Le Clerc, who was gunsmith to the late king of France, and well informed upon every subject that relates to his profession; they were communicated by him to Mons. De Marolles.

These experiments were made with a barrel which was thirty French inches in length, (nearly thirty-two English measure,) and weighed, together with the loaded plank upon which it was fixed, twenty-eight pounds. The barrel had four touch-holes which could be stopped with screws. The charge consisted of one drachm and twelve grains of powder from a royal manufactory, and of one ounce eighteen grains of shot called small 4.

This was fired at a sheet of paper measuring twenty inches by sixteen, French measure, placed at the distance of twenty-eight toises, or nearly forty-five ordinary paces. The only difference was, that in the first set of experiments the wadding consisted of card-paper, and in the second of hat, both cut to fit the caliber.

Had these trials been made with no other view than to determine the degree of recoil produced by the different situation of the touch-hole, there would have been no use in marking the size of the shot, the distance and dimensions of the mark, and the number of grains thrown into it at each discharge. It was, however, intended to try, at the same time, how far the equality of the discharges could be depended upon, with regard to the number of grains that struck a given space; and we shall have occasion hereafter to make re marks upon the result of the trials in this respect.

N. B. The French foot is three quarters of an inch longer than the English foot, and the French inch is divided into twelve lines.

We have thought it better to inform the reader of this, and leave the table as it is, than to make any fractions in the numbers by reducing it to English measure.