GENERAL REPORT OF THE JUDGES OF GROUP XVI. 4 g PRESSURES INDICATED BY THE CRUSHER-GAUGE IN THE 12.5-INCH RIFLED M. L. GUN. Charge 130 pounds of 1.5 inch cubical powder. Projectile 800 pounds. No. OF Round. Muzzlk Velocity. Pressure in Tons per Square Inch at Various Points from end of Bore. REMARKS. 0 12 inches. 24 inches. 36 inches. 48 inches. 60 inches. 1401 22.3 21.4 20.3 20.1 14.1 12.0 New copper cylinder. 2 22.7 22.8 20 4 21.1 14.9 12.1 Same coppers as used in round 1. 3 1408 22.7 22.9 20.5 21.3 16.1 12.3 Same coppers as used in rounds 1 and 2. 4 1424 22.7 22.9 22.4 23.6 17.1 12.7 Same coppers as used in rounds 1, 2, and 3. These experiments corroborate those made previously on the same subject by General Rodman. 2. The use of unsuitable descriptions of powder, or even of ex cessive charges of slow-burning powder, may give rise to oscillations of pressure termed “ wave action,” which act violently on local points in the powder-chamber without contributing to the useful effect of the charge. 3. If powder be burned uniformly in the gun without indication of wave action, the pressure will increase with the increase of charge,— at first very rapidly, but after twenty tons on the square inch has been exceeded, then very slowly. 4. With a suitable charge for the gun, the pressure in the powder- chamber increases slowly but steadily with the increase in weight of the projectile up to a certain point: beyond this point no material increase of pressure can be obtained by increasing the weight of the projectile. 5. As already stated, the greatest amount of work heretofore real-, ized in any gun resulted in firing the 8o-ton Woolwich rifled muzzle- loading gun with a charge of 350 pounds and a projectile 1703 pounds in weight. In this case the muzzle velocity was 1505 feet, total muzzle energy 26,740 foot tons, and mean pressure in the powder- chamber 20.4 tons on the square inch. The Krupp 14-inch breech-loading rifled gun has realized a muzzle energy of 21,300 foot tons in firing a charge of 297.6 pounds, and shot of 1146.4 pounds, the pressure being 25.9 tons on the square inch. 6. Experiment has shown that the pressure produced by the explo sion of large charges can be varied and controlled by mechanical alterations in the form and density of the gunpowder used. It has also been proved that hydraulic power can be easily applied to the service of the heaviest guns. We may, therefore, conclude that the size of heavy rifled ordnance will go on steadily increasing, and will only be limited by practical requirements. 4 , tidier ■