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bail win be expilicd more forcibly. This difchnrge is cf- 

 fcfted by means of a lock. /■ / {fg. IJ.) placed here as in 

 other RUDS ; for the trigger being puUtd, the cock /• will 

 go dow'.i, and drive a lc\>.r o, that will open the valve, and 

 let in the air upon the bullet K. 



An .lii-gyn nf the mod modern and approved conftniclion 

 is reprelented \njig. l6. A is the iron gun-barrel, witli the 

 lock, ilock, ram-rod, &c. of alxnit the fi/.e and weight of 

 a common fowling-piece. Under the lock at h is a round 

 fleel-tube, with a Iniull inovealile pin in the inlidc, which is 

 pulled out by the fpring of the lock, when the trigger a 

 is pulled. To this tube, b, is fcrcwed a hollow copper-ball, 

 f, containing a fpring-valve at its aperture ; and perfectly 

 nir-tiglit. Each gun has ufually two of thefe balls, which 

 are fnl'y charged with condenfed air by means of the con- 

 denfuig fyringe B, fg. 17. Having rr.wimed down the 

 leaden bullet into the barrel, and fcrewed the copper ball 

 home to the h>ck at b, let the trigger, a, be pulled, and 

 the pin at b will be forcibly and inftaiitly driven out againlt 

 t!te valve in the ball, and will thus liberate a portion of the 

 condenfed air ; vhich, milling up through an aperture in 

 the lock into the barrel immediately bcfm-e the ball, will 

 impel it to the dillance of, at leall, 60 or 70 yards. By 

 recocking the piece, another difcharge may be immediately 

 wade, and thus repeated 15 or 16 times, with a very imall 

 Iiifling noife, which at a diilance is not audible. The con- 

 denfed air is forced into the bail by the following apparatus. 

 The ball, c, is fcrewed to the brals fyringe B (fig. 17.) 

 t^uile clofe. In this fyringe is adapted a moveable plllon 

 a.nd i'on rod, a, at the end of which is a ilrong ring, into 

 v/iiich is placed a flout iron rod, k k : upon tills rod the feet 

 are firmly placed, and the hands are applied to the wooden 

 handles, / /, fixed to the fyringe. By ilcadily moving the 

 barrel B, up and down on the rod a, the bal'., c, will 

 ':iecome charged writh condenfed air ; and it is eafily known 

 when it is filled to the iitmoft by the inellitible action which 

 the air makes againil tlie pillon, when you are working the 

 fyringe. At the end cf the rod k, is ufually an eight-fquare 

 hole, which ferves as a key to make the ball fall on the 

 fcrew, b, of the gun, and on the fyringe. The piflon-rod 

 \^orks air-tight by a collar of leathers on it, in the barrel, 

 IJ ; and therefore, when the barrel is pulled up, frefli air 

 will ru(h in at the hole b ; when the barrel is pufhed down, 

 the air in it can only pafs into the ball at top ; the barrel 

 being drawn upwards, the operation is repeated, until the 

 .-Cndenfation is fo Ilrong as to refill the aftion of the piflon. 



Dr. Macbride (Exper. EfT. p. 8j.) mentions an improve- 

 :rient of the air-gun bv Dr. Ellis, in which the chamber for 

 ( ontaining the condenfed air is not in the flock, which makes 

 the machine heavy and unwieldy, but has live or fix hollow 

 ipheres belonging to it, of about three inches diameter, 

 fitted to fcrew on the lock of the gun. Thefe fpheres are 

 contrived with valves for confining the air, which is forced 

 into their cavities, fo that a fenant can cany them ready- 

 charged with condenfed air j and thus the gun of this con- 

 llruftion is rendered as light and portable as one of the 

 fmallell fowling-pieces. 



The magazine air-gun is an improvement of the common 

 air-gun, invented by an ingenious artift called L. Colbe. 

 By his contrivance ten bullets are fo lodged in a cavity, near 

 the place of difcharge, that they may be drawn into the 

 fhooting barrel, and fucceffively iTiot fo quickly, as to be 

 nearly of the fame ufe with fo many different guns; the 

 only motion required, when the air has been previoufly 

 injefted, being that of fhutting and opening the hammer, 

 and cocking and puUing the trigger. In fg. 1 8, is exhi- 

 bited a fcftion of the gun, as large in every part as the gun 



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itfclf ; and fo much of its length is (licwn as is nfceffary 

 to give a complete idea of the whole. A E K is part of 

 the ilock ; G is the end of the injeflion fyringe, with its 

 valve, H, opening ivito the cavity, F I F F, between the 

 barrels. K K is the fniali or fliooling barrel, which receives 

 the bullets, one at a time, from the magazine, E D, which 

 is a ferpentine cavity, wherein tiic bullets, b, b, &c. are 

 lodged, and glofed at the end D. The circular part, S I j * M/, 

 is the key of acock, having a cylindrical hole, I K, through 

 it, equal to the bore of the fmall barrel, and forming a part 

 of it in the prefent fituation. When the lock is taken off, 

 the feveral parts, Q, R, T, S, W, &c. come into view, by 

 means of which the aifcharge is made, by pufliing up the 

 pin, P/i, which raifes and opens a valve, V, to let in the 

 air againil the bullet, I, from the cavity, F' F F; which valve 

 is immediately fliut down again by means of a long fpring 

 of brafs, N N. This valve, V, being a conical piece of 

 brafs, ground very true in the part which receives it, will 

 of itfelf be fufficient to confine the air. To make a dif- 

 charge, pull the trigger, Z Z, which throv\'s up the feer, 

 V X, and difcngages it from the notch, x ; upon which the 

 ilrong fpring, ^V W, moves the tumbler, T, to which the 

 cock is fixed. The end, u, of this tumbler bears down the 

 end V, of the tumbling lever, R, which, by its other end, m, 

 raifes the flat end, /, of the horizontal lever, Q_, by which 

 means the p:n, P/>, is pufhed up, and opening the valve, V, 

 dlfcharges the bullet ; all which is evident from a bare view 

 of the figure. 



To bring another bullet inflantly to fucceed I, there is a 

 part H, called the hammer, reprefented 'in fig. 19. ^ni.Jig. 20. 

 wliich by a fquare hole goes upon the fquare end of 

 the key of the cock, and turns it about fo as to place the 

 cylindric bore of the key I k, in any fituation required. 



Thus, when the bullet is in the gun, the bore of the key 

 coincides with that of the barrel K K ; but when it is dif- 

 charged, the hammer H is inflantly brought down to fhut 

 the pan of the gun ; by which motion the bore of the key 

 is turned into the fituation //■, fo as to coincide with the ori- 

 fice of the magazine ; and upon lifting the gun upright, 

 the ball next the key tumbles into its cavity, and falling 

 behind two fmall fprings, s s, fig. 18. is by them detained. 

 Then opening the hammer again, the ball is brought into 

 its proper place, near the difcharging valve, and the bore of 

 the key again coincides with that of the ihooting barrel. It 

 appears how expeditious a method this is of charging and 

 diicharging a gun ; and if the force of condenfed air was as 

 great as that of gunpowder, fuch an air-gun would ac- 

 tually anfwer the end of many guns, and prove the befl de- 

 fence cigainil highwaymen or robbers ; becaufe, when there 

 is reafon to fufpett them, they might then make five or fix 

 difcharges before the robber can come within pidol-fhot. 



From the experiments of Mr. Robins, in his New Prin- 

 ciples of Gunnery, (See Mathem. Trafts of Robins, by 

 Wilfon, vol. i. p. 73.) it appears, that the force of gun- 

 powder, at the moment of its explofion, is 1000 times 

 greater than that of the elaflicity of common air ; and, 

 therefore, that the latter may produce the fame effeft with 

 the former, its condenfatlon niufl be 1000 times greater 

 than that of its natural flate. But as the velocities with 

 which equal balls are impelled are diredlly proportional 

 to the fquare roots of the forces, the velocity with which 

 an air-gun, coutaining air condenfed only ten times, will 

 projeft a ball, will be xotli °f that arifing from gun-powder ; 

 and if the air were condenfed 20 times, it would com- 

 municate a velocity of ith of that of gun-powder. In 

 the air-gun, however, the refersoir of condenfed air is 

 commonly veiy large, in proportion to the tube which 

 6 contains 



