Page:Popular Science Monthly Volume 13.djvu/293

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RECENT EXPERIMENTS ON FOG-SIGNALS.

gunpowder, had slight advantage over 1 pound of gun-cotton detonated in the open; while the 12-pound howitzer and the 18-pounder were both beaten by the gun-cotton. On the 2d of May, on the other hand, the gun-cotton is reported as having been beaten by all the guns.

Meanwhile, the parabolic muzzle gun (Fig. 3), expressly intended for fog-signaling, was pushed rapidly forward, and on the 22d and 23d of March, 1876, its power was tested at Shoeburyness. Pitted against it were a 16-pounder, a 512-inch howitzer, 112 pound of gun-cotton detonated in the focus of a reflector, and 112 pound of gun-cotton detonated

PSM V13 D293 Fog warning sound reflector.jpg
Fig. 3.—Gun-Cotton Slab (112-lb) detonated in the Focus of a Cast-iron Reflector.

in free air. On this occasion, nineteen different series of experiments were made, when the new experimental gun, firing a 3-pound charge, demonstrated its superiority over all guns previously employed to fire the same charge. As regards the comparative merits of the gun-cotton fired in the open, and the gunpowder fired from the new gun, the mean values of their sounds were found to be the same. Fired in the focus of the reflector, the gun-cotton clearly dominated over all the other sound-producers.[1]

The whole of the observations here referred to were embraced by an angle of about 70°, of which 50° lay on the one side and 20° on the other side of the line of fire. The shots were heard by eleven observers on board the Galatea, which took up positions varying from 2 miles to 1312 miles from the firing-point. In all these observations, the reënforcing action of the reflector, and of the parabolic muzzle of the gun, came into

  1. In this case the reflector was fractured by the explosion, but it did good service after fracture.