321 GtfNDERODE rently to the chlorate of potassa powders. Little is known of its application. A new gun cotton, known as gadoxyline, is manufac- tured in Wolverhampton, England. Its com- position is unknown. Gun cotton has been manufactured into an explosive paper, to re- duce the danger of handling and charging. G&NDERODE, Karoline TOD, a German poetess, born in Carlsruhe, Feb. 11, 1780, committed suicide July 26, 1806. She became canoness of a chapter in Frankfort, and under the name of "Tian " wrote a number of poems remarkable for passionate feeling. She formed an attach- ment for the philologist Creuzer, which termi- nated unhappily, and led to her suicide. She was intimate with Bettina von Arnim, who published their correspondence under the title of Die Gunderode (2 vols., Grilnberg, 1840; translated by Margaret Fuller, Boston, 1842). Her literary remains consist of Gediehte und Phantasien (Hamburg, 1804), PoetiscJie Frag- mente (Frankfort, 1805), and Gesammelte Dich- tungen (Mannheim, 1857). GUNDUK,ariver of Hindostan, which rises N. of the Himalaya mountains, and flows through that chain in a S. E. direction to Hajeepoor, where it falls into the Ganges, in lat. 25 39' N., Ion. 85 16' E. Its course is estimated at 400 m. The scenery where it emerges from the Himalaya range is magnificent. In the upper part of its course it is called Salgrami, from a singular species of stones found in its channel ; they are mostly round, and are gen- erally perforated in one or more places. CUNDWANA. See GONDS. GUNNEL. See BLENNY. GUNNERY, the art of using guns, gunpowder, and projectiles. The forces which are of mo- ment in gunnery as affecting the course of projectiles are terrestrial gravitation and the resistance of the air. The former is so nearly uniform, both in amount and direction, that it may be so regarded. But the difficulties which appear when we investigate the resis- tance of air are so formidable, that hitherto mathematicians have utterly failed to find a general formula, and have been obliged to re- sort to purely empirical methods. The first quantity to be sought is a unit of resistance with which all other degrees of resistance may be compared ; and this is usually taken as the resistance offered by the air to a body having a front 1 foot square, moving 1 foot in 1 second. This quantity cannot be determined theoreti- cally, but it is found by careful trial that the value of this unit depends upon the form of the front, as well as its area. It is also consid- erably influenced by the shape of the rear. Hutton has given the following ratios between the values of the resistance: Hemisphere, convex side foremost 119 Spli.-n- 124 Cone, point foremost, with a vertical angle of 25 42'. 126 Disk 285 1 [emfephere, flat surface foremost 288 Cone, base foremost 291 GUNNERY In these ratios it appears that the resistance to the cone is about the same as that to a sphere, notwithstanding the sharp point of the former. From recent experiments by Prof. Bashforth of "Woolwich, it also appears that the resistance to an elongated shot with a hemispherical front is less than that to a spherical shot of equal diameter, in the ratio of 1*345 to 1*531. NWton, in his Principia, gives as the front of least resistance a figure having nearly the section of a pointed Gothic arch. In practice it has been found that the " pointed ogive " or pointed Gothic arch gives less resistance than any other front hitherto ex- perimented with. Investigators have therefore been compelled to determine the values of the unit independently for every kind of projectile in use. The dependence of resistance of air upon velocity is also determined experimentally. The latest and most trustworthy researches, by Prof. Francis Bashforth of the Woolwich artillery school, show that for velocities rang- ing from 1,400 to 1,700 ft. a second the re- sistance varies nearly as the square of the ve- locity ; for those between 1,100 and 1,400 ft. it varies more nearly as the cube of the velocity ; while for still lower velocities the ratio is in some power higher than the cube. Thus a 15-inch shot, moving 1,500 ft. a second, en- counters a resistance amounting to nearly a ton and a half, while a 10-inch shot encounters about three fourths of a ton at the same velocity. The amount of resistance offered by the air, and many other important data in gunnery, are ascertained by measuring the velocity of a pro- jectile in different parts of its path. This is accomplished by means of an electro-veloci- meter. The projectile is made to break a series of electric circuits at several points, separated by equal intervals. The electric circuit passes through a machine, which contains a cylinder revolving at a known rate, and by appropriate devices the ruptures of the circuit make visible marks upon this cylinder. By measuring the distance between these marks, and multiplying it by the rate of revolution, the time which elapsed between any two instants of rupture becomes known. Besides retardation, projec- tiles moving in air are subject to deviations re- sulting from their rotary motions about their axes. Spherical shot are always made of smaller diameter than the bore of the gun from which they are fired; the difference in the two diameters being termed windage. One of its consequences is, that spherical shot are subject to a series of rebounds from side to side or from top to bottom of the bore, which is called balloting, and which causes them to leave the bore with a rotary motion. Let us suppose, for instance, that at the last ballot (rebound) the shot strikes the right side of the bore, as in fig. 1, receiving a rotary motion in the di- rection indicated by the arrows. This motion, combined with the motion of translation, tends to augment the pressure of the opposing air in the direction A Z, and to diminish it in the di-
