Page:The American Cyclopædia (1879) Volume I.djvu/830

 794 ARTILLERY metal is increased ; all the parts are annealed. Blakely guns are rifled with one-sided grooves, and are fired with expanding projectiles. The principal calibres are the 700, 550, 350, 250, 200, 120, and 100-pdrs., the diameters of the bore varying from 12 inches to 6-4 inches, and the weights of projectiles from 700 to 100 Ibs. Palliser's manner of making a gun consists in introducing into a cast-iron gun a hollow cylin- der of coiled wrought iron, of such thickness in proportion to its calibre that the residual strain borne by the tube has such a relation to the strain it transmits to the surrounding cast iron as is best proportioned to their respective elasticities; and by varying the thickness of the tube, the transmitted strains can be regulated with the greatest nicety. In the larger guns he proposes to use two or more concentric tubes; in the very largest, three tubes, the inner one to be of the softest and most ductile wrought iron, the next of a stronger and harsher quality, and the third of steel for some distance in front of the chamber. Old smooth- bored guns, chiefly 68-pdrs., reamed out and strengthened in this way, have shown remark- able endurance, and have been thus utilized in large numbers. Parsons's plan of conversion consists in introducing a tube with a jacket, both of steel, through the breech of a gun, which is afterward stopped up by screwing in n large cascabel ; though stronger than Palliser's method, it is much more expensive. Mon- criefFs counterpoise gun carriage is designed to shield heavy guns from direct tire, and enable them to be loaded under cover. Having given satisfactory results upon its trial in 1868, tho British propose to use it extensively for coast defence, particularly in low sites where the batteries are but little above the water level. The top carriage rests on a strong bolt con- necting two elevators, curved in rear, and with a box between them for the counterpoise, which is rather heavier than the gun. Upon firing the recoil makes the elevators roll backward on the chassis, the gun descending and the counterpoise rising. The weight of the latter gradually checks the motion and brings the piece to rest below the parapet, where a brake holds the elevators down until the loading is completed. During the past decade the Prus- sian artillery bus taken the foremost place, a consequence in great part of Krupp's ex- cellent system of breech-loading rifled can- non. The Krupp guns are made of cast steel, composed of puddled steel and pure wrought iron, melted in crucibles and then run into large ingots, which are worked under pow- erful steam hammers ; the fermature consists of a block sliding in a horizontal mortise crossing the bore, which is continued through the gun ; the gas check is a steel ring, which by its expansion prevents the escape of the gas. In loading, the breech block is only drawn out far enough to allow the charge and projectile to pass through a hole in its end ; an exterior lever working on a hinge starts the block, which being guided by proper grooves can be readily moved in or out. The rifling is poly- grooved, the lands being very much narrowed at the breech, which relieves the initial strain Fio. 11. Krupp Gun. due to the forcing of the projectile into the grooves. The various calibres are forged from a single ingot up to the 9-inch, in which the trunnion ring is a separate forging; the larger guns are built up by shrinking successive hoops ! of steel over a central steel tube, the fermature in the experimental 14-inch being slightly mod- ified so that the charge and projectile are in- serted at the side of the breech instead of through the end. The Krupp projectiles are of cast steel lead-coated, and take the rifling at four raised rings on their surface. The deep grooves cut in the steel to retain the lead re- duce the strength of the shells so much that they can only contain very small bursting charges compared with those of other systems ; the Armstrong and Whitworth 9-inch shells carrying charges of from 10 to 14 Ibs., while that of the Krupp 9-inch is less than 4 Ibs. The Krupp cannon sometimes use Gruaon's chilled iron projectiles. Krupp sixes and fours, firing 13'8-lb. and 8'5-lb. projectiles respec- tively, were adopted in the Prussian field ar- tillery in 1864, and gave so much satisfaction that they were exclusively used in the war of 1866 with Austria, although one third of the Prussian batteries were then armed with the old 12-pdr. smooth-bore. In the late war with France the marked superiority of the Prussian field guns was greatly enhanced by the skilful manner in which they were han- dled. The principal battles, from Weissen- burg and Forbach to Gravelotte, Beaumont, Sedan, and Metz, as well as the engagements with the French army of the north and sec- ond army of the Loire, were to a great extent a scries of artillery combats ; and both French and Prussians attribute the unprecedented suc- cesses of the latter mainly to the artillery, which whenever practicable was employed in mass. At Worth a grand battery of 96 guns covered the overwhelming attack on MacMa- hon ; near Gravelotte over 300 guns deployed on the road to the right of St. Privat and