GUM'TI, a river of India, remarkable, as its name is meant to express, for its wind ings, rises in a small lake in lat. 28° 35' n., and long. 80° 10' e., and after a south eastern course of 482 m., enters the Ganges from the left in lat. 25° 29' n., and long. 83° 15' east, It is navigable for inland craft as far up as Lucknow, which is fully more than 30) m. above its confluence with the Ganges. At Jaunpore, about 56 m. from the Ganges, it is spanned by a bridge of 16 arches.
GUN, a term applied in its most general application to firearms of any description, but in thq, more restricted and technical sense to Cannon (q. v.). A gun is a frustum of a right cone, with a cylinder excavated round the axis, to serve as a bore. Close home to the end of this cylinder, the powder is driven, and outside it is the ball to be expelled.
The trunnions are cast in one mass with the piece, and arc placed in the second rein force in such a position that the breech-end of the gun outweighs the muzzle. Their axis is generally about half their diameter below the axis of the piece. This locality has several conveniences; but for the maximum of steadiness in the recoil, it has been shown that the axes of the trunnions and of the gun should exactly intersect. The use of the trunnions is to suspend the cannon on its carriage in such a manner that it may be readily depressed or elevated, but so that it shall have no horizontal motion which is not shared by the whole carriage.
The vent or touch-hole, the channel through which the charge is fired, is a small cylindrical orifice leading at an angle from the breech of the bore towards the base ring. '[lie explosion within reacts with great force on the lower portion of the vent, .Ind in
case of rapid or long-continued firing, soon honeycombs the iron or brass, often dis lodging considerable fragments. Tins, besides diminishing the regularity of the action of the powder on the projectile, would involve danger of bursting if permitted to any great extent. The gun so affected is therefore bouched, that is,. has a new vent con structed. The process consists of drilling a female screw, of larger than the required diameter, in the metal of the gun. Into this matrix, a bar of pore copper is screwed (copper being the metal least liable to fuse under the intense heat of ignited gunpow der), and the vent is then drilled through the copper. Sir A. Dickson devised the fol lowing simple mode: he rammed a cartridge of sand firmly into the hreech. then filled the vent and all the interstices with molten copper, and had only to bore a hole through the latter to complete pie operation. In cases of great urgency, even this simple pro cedure may be shortened by the insertion of the stein of a tobacco-pipe during the tilling; the pipe, when removed, leaves a perfect vent.
With reference to rifled cannon, some particulars have already been given under AnnsTitoNG GUN, and fuller details will he given under RIFLED ARMS. Under the heading CANNON will be found some details as to various kinds of heavy guns, as well as under the several headings LANCASTER Gux, MORTAR, SHELL-GUN, etc. Thellistory of guns and gunpowder is sketched in the article. FIREARMS. For the ordnance now in use in the British army and navy, see WAR SERVICES. The various kinds of small-arms are discussed under their respective heads, as ARQUEBUS, MATCH-LOCK, PISTOL, REVOL