101 
GUN. 
than from the other defetts, it ou^ht to be particularly 
guarded againft. The elaftic fluid which is let loofe 
by the inflammation of the powder, and which endea¬ 
vours to expand itfelf equally in every diredtion, being 
repelled by the ftronger parts, adts with additional force 
againft the weaker ones, and frequently burfts its way 
through them; which would not.have been the cafe, 
had the Tides been of jhe fame •thicknefs and ftrength, 
and afforded an equal repercuflion. The weaknefs 
of any part of the barrel, occafioned by the inequality 
of the caliber, will ftill more certainly be the caufe of 
burfting than that produced by the filing; becaufe the 
inflamed fluid, being fttddenly expanded at the wider 
part, muft fuffer a compreflion before it can pafs onward, 
and the whole force is then exerted againft the weak 
place ; for gunpowder adts as the radii of a circle, and 
exerts the fame force on every part of the circumference 
of the circle. The conclufion to be drawn from all this 
is, that a thin and light barrel which is perfedtly up¬ 
right, that is, of equal thicknefs in every part of its cir¬ 
cumference, is much lefs liable to burft than one which 
is confiderably thicker and heavier, but which, from 
being badly filed or bored, is left of unequal ftrength 
in its Tides. 
In all that we have hitherto faid upon the caufes of 
burfting, the bad-quality of the iron has not been taken 
into apcount; and we do not know any means of infur- 
ing'againft thefe defedls, whether arifing from the bad- 
nels of metal, or from the infufficiency of workmanlhip, 
except by purchafing from a gunfmith of eftabliflied re¬ 
putation, and giving a good price for the piece. But 
by this we do not mean to fanCfion the pradtice of many 
of the gunfmiths in the fafhion of the day : we are con¬ 
fident in our opinion, that moll of their barrels are made 
too thin; and it may be fairly doubted, whether they 
have at all improved the quality of the metal. In 
fome experiments made with a barrel of the celebrated 
Lazaro Cominazzo, before-mentioned, and which was 
five feet ten inches in length,, and extremely thin, parti¬ 
cularly towards the muzzle, it was obferved, that the 
barrel vibrated fo much after the explofion of the charge, 
as- to produce a ringing found that might be heard to a 
confiderable diftance from the barrel. And yet this 
piece, notwithftanding its extreme thinnefs, was fired 
with very high charges. The iron appeared to be of 
an extraordinary fine quality, which goes to prove that 
the cohefion of the particles of the metal is the force 
which refills that of the powder; and hence great ad¬ 
vantage might be drawn to the manufacture of barrels, 
from an accurate knowledge of the force of powder, 
and the velocity of the ball. , For, thefe points being 
©nee determined, it might be known how ftrong the bar¬ 
rel Ihould be, by which all unneceffary wade of metal 
might be fpared on the one hand, and all danger avoid¬ 
ed on the other. For a force equal to t that which impels 
the ball, is exerted on the infide of the piece ; and, if 
the barrel has not fuflicient ftrength to refill this force, 
it muft: of neceflity go to pieces. 
Of the RECOIL. 
The mod frequent caufe of excefs in the recoil is, 
the bore of the piece being wider at one place than an¬ 
other : for, although this inequality be fo fmall as to be 
imperceptible to the eye, the repulfe, which the ex¬ 
panding flame meets with whenjjalling from the wider 
to the narrower part, renders hie 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 fame, the recoil 
will be in proportion to the quantity of the powder, and 
the weight of the ball or fhot; and that, with the fame 
charge, the recoil will be in proportion to the weight 
of the piece : or, the lighter the piece, the greater the 
VOL. IX. No. 569. r 
recoil. In plainer language, the impelling force of 
the gunpowder is the’firft and mod fimple caufe of fire¬ 
arms recoiling ; for this force ads equally on the 
breech of the piece and on the ball ; fo that, if the 
piece and ball were of equal weight, and other cir- 
cumftances the fame, the piece would recoil with the 
fame velocity as that with which th-e ball ift'ues out of 
the piece. 
For the fame reafon, whatever retards the exit of the 
charge operates like an increafe of lead, and, by con¬ 
fining the force of the explofion the more to the barrel, 
produces a greater recoil; hence partly it is, that in 
proportion as the barrel becomes foul within by re¬ 
peated firing, the recoil increafes. A piece will recoil, 
if, from the breech-plug being made too fhort, there re- 
main”fome turns of the ferew not filled up ; thefe hol¬ 
lows, wherein a part of the powder is lodged, forming 
an obftacle that confines and retards the explofion. A 
barrel mounted on a ftock that is very ftraight, will re¬ 
coil more than when mounted on a ftock that is confi¬ 
derably bent; as the curvature ferves to break and dea¬ 
den the force of the recoil; and, fometimes alfo, a fowl¬ 
ing-piece will recoil from the fliooter applying it im¬ 
properly to his flioulder; for, if the butt is'not ap¬ 
plied clofely to the flioulder, or is applied fo as to be 
fupported only at a Tingle point, the recoil will be much 
more fenfibly felt than when the hollow of the butt em¬ 
braces the Ihoulder, and is firmly fupported by the 
weight of the body. Guns are obferved to recoil more 
after being fired a number of times than they did at the 
beginning. The matter, which is left upon the infide 
of the barrel after tire explofion, and which increafes 
on every difeharge, attracts moifture very quickly ; es¬ 
pecially if the faltpetre employed in the' powder was 
not well purified from the admixtures of common fait 
which it contains in its rough ftate. This moifture be¬ 
comes confiderable after a few difeharges, and, being 
formed into vapour by the heat during the explofion,, 
adds its expanfive effort to that of the inflamed powder, 
and greatly increafes the agitation and recoil. Owing 
to this caufe, probably, rather than to that before-men¬ 
tioned, arifes the recoil from fome turns of the breech- 
ferew not being filled up by the breech-plug, and there¬ 
by affording a lodgment to moifture. 
Among the variety of caufes to which the exceflive 
recoil of pieces has been attributed, there is one which 
yet remains to be confidered; this is, the touch-hole’s 
being placed at fome diftance from the breech-plug/ f@ 
that the powder, inftead of being fired at its bale, is 
fired near the centre of the charge ; whence, itis'faid, 
the recoil is increafed, and the force of the.difeharge 
weakened, by the effort of the powder being exerted 
more upon the breech than upon the ball or fhot. 
With this idea in view, fome gunfmiths form a channel 
or gropve in the breech-plug, as deep as the fecond or 
third turn of the ferew; the touch-hole opens into thi3 
channel, and the powder is thereby fired at its very 
loweft part ; and this, they aflert, increafes the inflam¬ 
mation and the force of powder. That the diftance of 
the touch-hole from the breech, however, has very lit¬ 
tle if any fhare in the increafe of the recoil, we fhall 
prove in the moll fatisfadlory manner from experiments 
made purpofely to determine this point. As to the 
idea, that the force of the difeharge is diminijked by the 
increafe of the recoil, it is too abfurd to require difeuf- 
fion : the force exerted by the powder upon the breeqh, 
is always equal to that which it exerts upon the ball or 
fhot; fo that, if there be nothing in the barrel that re¬ 
tards the exit of the ball, an increafe in the recoil will 
be always attended with an increafe in the force of the 
difeharge. 
The following experiments were made by Motif. L'e 
Clerc, who was gunfmith to the late king of France, 
and well informed upon every fubjedt that relates to 
D-d his 
