The nitro-substitution explosives are made from nitrobenzenes, nitrotoluenes, nitronaphthalenes, nitrophenols, and bodies of a similar character, and one of them, called joveite, has given excellent results in this country. After having demonstrated that the destructive effect of joveite was greater than that of gunpowder, smokeless powder, or gun cotton, and, by repeated trials under severe conditions, that service shell loaded with it could be fired from service guns under service conditions with safety, on November 3, 1897, the naval officials at Indian Head fired a fused ten-inch Carpenter armor-piercing projectile containing 8.25 pounds of joveite, with a velocity of 1,960 foot-seconds, at a Harveyized nickel-steel plate taken from the armor for the United States steamship Kentucky. The shell passed completely through the armor plate, where it was 14.5 inches in thickness, and burst immediately behind the plate. In a second round an unfused ten-inch Midvale semi-armor-piercing shell containing twenty-eight pounds of joveite was fired with a velocity of 1,925 foot-seconds at the same plate where it was sixteen inches thick. The shell penetrated to a depth of twelve inches, and the heat produced by the upsetting of the shell was so great as to explode the joveite, which broke the plate and burst the shell with tremendous violence. In fact, the explosion was so very severe that the heavy base plug of the shell was sheared longitudinally, an effect never observed before with any explosive fired at the proving ground. [Illustration: SHOOTING AN OIL WELL WITH NITROGLYCERIN.] Notwithstanding that no accident occurred in any of the many firings, that the stability and safety of the explosive are assured, and that the explosion has been effected with a well-known and long-used form of fuse, no provision has yet been made to supply the service with charges for its costly armor-piercing projectiles. Happily, the force resident in explosives may be applied to the saving as well as to the destruction of human life, advantage having long since been taken of the penetrating power of the report from the discharge of a gun to employ them as signals of distress at sea or as warnings in foggy weather. The English Lighthouse Board, under Professor Tyndall’s guidance, some years ago sought to find the form of gun best suited to this purpose, and their experiments led them at first to a bronze gun with a bell-shaped mouth. Subsequently, their attention being called to the sharpness and carrying power of the report from detonating gun cotton, an apparatus was devised in which the gun cotton was detonated in the focus of a parabolic mirror. The best results, however, were attained with rockets carrying gun cotton charges arranged to be exploded in mid air. [Illustration: SAFE TO BE OPENED BY DETONATION OF NITROGLYCERIN. Before the charge was fired.] [Illustration: AFTER FIRING CHARGE.]