RIFLE GUNS. 



the pole of the circular motion than on the other ; yet, as 

 the place where this greater refiltancc adts mult perpetually 

 fhift its pofition round the line, in which the bullet (lies, 

 the dt-fledtion, which this inequality would occafion, if it 

 afted conflantly with the fame given tendency, is now con- 

 tinually rectified by the various and contrary tendencies of 

 that ditturbing force, during the courie of one revolution ; 

 fo that the ball will always go right forwards, and thus 

 that deflection or deviation, already taken notice of under 

 the article Projectile, and in the preceding part of this 

 article, will be prevented. This may be explained by the 

 motion of an arrow ; for if an arrow that is not feathered 

 be (hot from a bow, its motion will be very irregular ; but 

 when the feathers of the arrow are properly arranged in a 

 fpiral form, fo as to make the arrow fpin round its axis, it 

 will always fly ltraight forward. Upon the fame principle, 

 every fchool-boy finds himfelf under the neceflity of making 

 his flluttle-cock fpin, before he can depend upon the truth 

 of its flight. Mr. Robins obferves, that the actual motions 

 of bullets difcharged from rifled pieces correfpond very 

 well with thefe fpeculations. Although the ufe of pieces 

 of this kind had long prevailed in Europe, particularly in 

 Germany and Switzerland, the advantages refulting from 

 them have been very imperfectly underltood, and, as 

 Mr. Robins obferves, unaccountably miireprefented. The 

 three following reafons have been conltantly alleged in 

 favour of this conftruftion : either that the inflammation 

 of the powder was greater by the refinance which the 

 bullet thus forced into the barrel gave it, and that by it 

 the bullet received a much greater impulsion than it would 

 have done. from the lame quantity of powder in a common 

 piece, or that the bullet, by the compounding of its cir- 

 cular and revolving motion, did, as it were, bore the air, 

 and thereby flew to a much greater diltance, than it would 

 otherwife have done ; or that, by the fame boring motion, 

 it made its way much cafier through all folid fubftances, 

 and penetrated much deeper into them, than if difcharged 

 in the common manner. But the ingenious writer juft 

 mentioned, fatisfied himfelf by numerous experiments made 

 with rifled barrels of various iizes, that none of thefe 

 reafons hold true in the ufe of fuch pieces ; but that the 

 advantage of their conllruftion refults from its preventing 

 the deflection of the ball, as we have above represented it. 

 And that it produced this effect he found by obferving, 

 that the fame hemifphere of the bullet which lies foremolt 

 in the piece, continued foremolt during the whole courfe of 

 its fli; 



In Germany and Switzerland, an improvement is made 

 in the m tliod, already recited, of charging thefe pieces; 

 efpecially thofe of the larger fort, which are ufed for 

 (hooting at great dillances. This is done by cutting a 

 piece of very thin leather, or of thin futtian, in a circular 

 fhape, fomewhat larger than the bore of the barrel. This 

 circular piece being greafed on one fide is laid upon the 

 muzzle with its greafy parts downwards, and the bullet 

 being placed upon it, is then forced down the barrel with 

 it ; by which means the leather or fuitian inclofes the lower 

 half of the bullet, and by its interpofil "on bet ween the bullet 

 and the rifles, prevents the lead from being cut by them. 

 But in thofe barrels where this method is pra&ilcd, the 

 rifles are generally lhallow, and the bullet ought not to be 

 too large. The rifle-barrels, which have been made in 

 England, where they are not very common, are contrived 

 to be charged at the breech, the piece being, for this pur- 

 pofe, made larger there than in any other part. Thi 

 powder and bullet are put in through the fide of the barrel 

 by an opening, which, when the piece is loaded, is filled op 



with a fcrew. By this means, when the piece is fired, the 

 bullet is forced through the rifles, and acquires the fame 

 fpiral motion as in the former kind of pieces ; other barrels 

 unferew at the breech, for the convenience of charging them. 

 With regard to the defects of thefe rifled pieces, Mr. Robins 

 obferves, that if either the angle of elevation, or the cur- 

 vature of the bullet's track through the air be great, the 

 inclination of the axis round which it whirls will caufc 

 irregularities, which will often produce confiderable de- 

 flections. Accordingly he propofes to make ufe of bullets 

 of an egg-like form, inftead of ipherical ones, and to fire 

 them with their broad ends foremod, that thus their longer 

 axes may be always carried, by their centres of gravity, 

 into the lines of their flight. Upon the whole, he con- 

 cludes, that whatever tends to diminifh the friftion of thefe 

 pieces, tends, at the fame time, to render them more com- 

 plete ; and confequently the lefs the rifles are indented, th, 

 better they are, provided that they are juft fufRcient to 

 keep the bullet from turning round in the piece. Belides, 

 the bullet ought to be no larger than to be jult prefled by 

 the rifles, for the cafier the bullet moves in the piece, fup- 

 pofing it not to fhift its pofition, the more violent and ac- 

 curate it j flight will be. And to render them in this refpeft 

 itill more complete, the fweep of the rifles fhould be in 

 each part exattly parallel to each other : for then, after 

 the bullet is once put in motion, it will Aide out of the 

 barrel without any fhake, and with a much fmaller degree 

 of fridtion than if the threads of the rifles have not all of 

 them the fame degree of incurvation. The foreigners are 

 fo exaft in this refpeft, that they try their pieces, with a 

 view to this particular, in the following manner : they firft 

 pour melted lead into them, and letting it cool, they pro- 

 cure a leaden cylinder of perhaps two or three diameters in 

 length, exactly fitted to one part of the infide of the piece ; 

 then if this leaden cylinder, being gently pufhed by the 

 rammer, will pafs from one end of the barrel to the other, 

 without asy fenfible (train or effort, they pronounce the 

 piece perfeft ; but if it any where lticks or moves hard 

 they efteem it defective. 



We have dated that fome rifle-pieces are charged at the 

 breech ; thefe, however, are neceffarily much dearer than 

 the others, and excepting the expedition in charging them, 

 are really inferior to thole in which the ball is introduced 

 at the muzzle, on which account they are not much 

 employed at prefent, at lead not in this country. The 

 want ot expedition in the charging pieces of this kind is, 

 however, a very ferious defect, to remedy which, it has 

 been propofed to have the balls cad with projections upon 

 them, in the fame manner as defcribed in the following 

 article on Rifle Ordnance. This may be done with great 

 eafe and accuracy, by making correfponding hollows round 

 the zone of the bullet-mould ; by this means the balls may 

 be fitted fo accurately to the rifles, as to leave fcarcely any 

 windage ; while the friction will be lefs than it is either 

 when the hall is put in at the breech, or forced in at the 

 muzzle. 



In treating of the caufes of aberration in the flight of 

 halls, we have fuppoied the air to he | at relt ; 



but it is evident that the fore- of the wind will affecl bi 

 confiderably, whether they are fired from a plain or a 



rifle barrel ; this effect, however, will be much lefs in the 

 latter than in the former; but in neither cafe is it pollible 

 either to avoid it entirely, or to cllim.ite the quantity of 



aberration that it may, under different circumdancea, 

 occafion. 



Pieces intended lor (hooting with hall, whether they 

 be plain or rifled, ought to be of much more equal tbii 



uefs 



