dynam

[Fr. dyname, from Gr. dynamis power.] Eng.: A term used to expre a unit of work equal to a weight of one pound raised through one foot of space in one second; a foot-pound. [DYNE.] dy-năm-ětěr, s. [Fr. dynamètre, from Gr. dy nam is power, and metron =a measure.] Optics: An instrument for measuring the magnifying power of a telescope. This power is the ratio ally for utilizing dynamite guns in naval warfare. vius , owned by the U. S. government. It was launched in 1888. It was built of unusually light scantling and plating, is long and narrow, and sits low in the water. It has powerful engines and attains a high speed. Its main armament consists of three pneumatic dynamite guns placed side by side, close together, in the forward part of the ship. These three parallel tubes are built into the ship, about 15 feet of the muzzles protruding above the forecastle deck, inclined at an angle of about 20 degrees, the ends of the muzzles of the tubes rising about 5 feet above the deck planking. The remainder of the tubes run down to the hold of the ship, where the compre ed air machinery is, and where the ammunition and the breech and loading mechanism are situated. The tubes are made of light cast iron, are 50 feet in total length and have an interior diameter of 15 inches. There are two air compre ors to compre the air that is used as the propellant to discharge the aerial torpedoes from the long tubes. The compre ed air begins to move the torpedos gradually and, rapidly increasing in propulsive force, drives the shot out of the long barrel at a high velocity. The great benefit derived from the slow, steady, gradually increasing pre ure of compre ed air is that it allows the use of thin gun barrels or tubes and the employment of immense quantities of the highest explosives. There is an absence of all shock and a consequent avoidance of the danger ordinarily connected with the firing of dynamite or gun-cotton. The guns, being immovably fixed in the ve el, cannot be trained and handled like other guns; they cannot be laid to hit the target by moving them to the right or left, or up and down; instead, the ve el itself must be maneuvered so as to get within the range. The charge of explosive used in the pneumatic dynamite gun is about 300 pounds of gun-cotton, and is held in the front end of a cigar-shaped shell 7 feet long and not quite 15 inches in diameter. The rear end of the shell is fitted with wings or fans to insure the torpedo's preserving its horizontality during its time of flight. This torpedo is loaded to the gun at the breech, near which there is a revolving chamber holding five other torpedos; hydraulic power is used to manipulate the carrier. Once in place and the breech closed, the air valve is opened, the compre ed air rushes into the firing chamber and away speeds the most deadly projectile man's ingenuity has thus far devised.