Principles of Gunnery: Rifled OrdnanceMitchell, 1879 - 115 pages |
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Expressions et termes fréquents
50 per cent angle of spiral angular velocity approximately armour-plate Bashforth calculated calibres cartridge centre of gravity charge of powder Chilled iron chronograph chronometer chronoscope coefficient common shell cylinder determined diameter direction disc distance drift electro-magnet elongated projectiles energy per inch equation experiments explosion flat-headed projectiles flight form of head given grooves gun and carriage half-gyration horizontal plane inch of circumference increasing twist instrument iron jectile lateral error length of bore M.L. gun Martini-Henry maximum pressure mean absolute error mean error moment of inertia motion muzzle velocity obtained ogival head Ordnance penetration perforate plate powder-chamber probable rectangle quarters of gyration R.A. Institution R.L.G. powder radius of gyration remaining velocity screens Shoeburyness square inch steel studs Suppose Table tangent target thickness tons trajectory trunnions uniform twist varies velocity of rotation vertical velocity weight of projectile windage wire wrought-iron zone containing 50
Fréquemment cités
Page 113 - E, the magnetism of the electro-magnet is destroyed, and the spring f carries back the keeper, which, by means of the arm a, gives a blow to the lever b. Thus the marker m is made to depart from the uniform spiral it was describing. When the current is restored the keeper is attracted, and thus the marker m is brought back, which continues to trace its spiral as if nothing had happened. E is connected with the clock, and its marker m
Page 112 - ... gives a general view of the chronograph. A is a fly-wheel capable of revolving about a vertical axis, and carrying with it the cylinder K, which is covered with prepared paper for the reception of the clock and screen records. The length of the cylinder is 12 or 14 inches, and the diameter 4 inches. B is a toothed-wheel which gears with the wheelwork M so as to allow the string CD to be slowly unwrapped from its drum. The other end of CD being attached to the platform 8 allows it to descend slowly...
Page 106 - Transverse grooves are cut at equal distances, something less than the diameter of the shot, as shown in the diagram. Staples of hard brass spring-wire (No. 14* or 15), are fixed with their prongs in the continuation of the grooves. Pieces of sheet copper A are provided, having two elliptical holes, the distance of whose centres equals the distance of the grooves. The pieces of copper A are used to connect each wire staple, as C, with its neighbour on each side. Thus, Fig.
Page 114 - ... spiral it was describing. When the current is restored the keeper is attracted, and thus the marker, m, is brought back, which continues to trace its spiral as if nothing had happened. E' is connected with the clock, and its marker, m!
Page 106 - About ^Vth of a second is required for the complete registration of such an interruption, the spring traversing about half an inch. - The shelf B is placed for the weights to rest against, partly to prevent them from being carried forward by the shot, but chiefly to prevent the untwisting of the threads which support the weights. The weights used were about 2 Ibs. each, and the strength of the sewing cotton for supporting them was equal to a stress of about 3 Ibs., which was sufficient to withstand...
Page 15 - Work on a body when it moves the body in the direction in which it is acting, and the amount of work done is measured by the product of the Force and the Distance moved in the direction of the force.
Page ii - ... of electric currents, upon a recording surface travelling at a uniform and very high speed...
Page 114 - ... down upon the paper. When an experiment is to be made, care is taken to see that the two currents are complete. The fly-wheel A is set in motion by hand, so as to make about three revolutions in two seconds. The markers m, m...
Page 102 - V. fig. 1 ), fixed in a recess of the spring, H, by means of the screw, N, which forms an axle upon which it can be turned so as to bring a fresh portion of the edge opposite the chronometer. The spring, H, can be cocked or restrained by means of the catch on one end of the lever, I.
Page 48 - ... the resistance to the hemispherical head was decidedly greater than that opposed to the remaining three forms. The resistance of the air to the hemispheroidal and the ogival heads varied so little that it was plain that any of these forms most serviceable in other respects might be safely adopted. The slight variations in the resistances to the three latter forms lead to the conclusion that the amount of resistance offered by the air to the motion of elongated shot is little affected by the more...