The wonders of modern mechanismA résumé of recent progress in mechanical, physical, and engineering science . block is secured in place bywhat is termed an interrupted screw, having alternate linesof threads and Ijlanks. By this arrangement, instead ofhaving to screw in the breech-block with numerous turns,it may be swung right into ])lace, and tightly fastened withone-tenth of a revolution. The arrangement of the threadsin the block is such as to distribute the strain as much aspossible The conical sha])e of the block is considered veryadvantageous, as allowing it to be directly hinged, where
The wonders of modern mechanismA résumé of recent progress in mechanical, physical, and engineering science . block is secured in place bywhat is termed an interrupted screw, having alternate linesof threads and Ijlanks. By this arrangement, instead ofhaving to screw in the breech-block with numerous turns,it may be swung right into ])lace, and tightly fastened withone-tenth of a revolution. The arrangement of the threadsin the block is such as to distribute the strain as much aspossible The conical sha])e of the block is considered veryadvantageous, as allowing it to be directly hinged, whereas,if it were cylindrical in shape, it would have to be with-drawn and then swung open—a loss of one complete mo- 106 WONDERS OF MODERN MECHANISM. tion. The projectile is loaded from a little hand-barrow,and the shell after firing is removed in the same way—apowerful extractor loosening the shell so that it can be re-moved from the chamber with a slight pull. This extractorconsists of a rod passing through one side of the gun, andfitting into the groove for the rim of the cartridge-case, in Fig. 1( ARMSTRONG GUN. such a manner that, when it is turned about its own axis,the fitted part acts as a lever or pry, and brings the car-tridge to the rear. The extractor is brought back to itsplace, as the breech is closed, by means of a strong helicalspring outside the gun. The gun itself is of wrought iron,the inner tube being of steel, iron-bound. A somewhat similar gun is the Nordenfelt, which ismade in smaller calibres, the one illustrated having a two- RECENT PROGRESS IN GUNS AND ARMOR. 107 and a-quarter-inch bore. It is shown with a halt-shield,as arranged for naval use, being designed to stand behinda breastwork a yard in height. It is five feet seven incheslong, and weighs less than five hundred pounds, yet it firesa six-pound shot with an initial velocity of a quarter of amile a second, with a fraction over half a pound of smoke- Fi(i
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Keywords: ., bookcentury1800, booksubjectmachinery, booksubjectmechanicalengi
