Rensselaer Republican, Volume 17, Number 15, Rensselaer, Jasper County, 18 December 1884 — BIG GUNS. [ARTICLE]

BIG GUNS.

How They Are Made at the Philadelphia Navy Yard. Not an anvil stroke or even the monotonous blowing of a forge-bellow 3 greets the ear as one walks’ through the vast iron-works into which the na-vv-yard has been turned by the action of Congress on the recommendation of the Secretary of the Navy. And yet there aro close upon 1,000 men handling the metal which has given its name to the present age. Iron and steel arc to he seen in every stage of manufacture, from the forge and foundry to the finishing shops. The priecipal feature of interest at present is the construction of the steel cannons for the new cruisers. Nearly 300 men are employed in the Ordnance Department, the main work of which is tuese guns. These'-are of four sizes, five, six, eight, aud ten inch in bore, aud twelve feet six inches, fifteen, twenty, and twenty-six feet long. The process through which they pass is astonishingly complicated to the uninitiated. The forge shafts are prepared away from here and brought in a more or less rough statp. The two larger sizes are imported from Europe, and come rough-bored and turned, this being necessary to enable the tempering to be done at the place where they are forged. 'The others are turned out in the rough by the Midvale Steel Works, Pennsylvania, and are rough-bored and turned here, being returned to the works again to have the “oil temper” given to them, without which they would hurst at the first discharge. When returned here they are bored out to within one-eighth of an inch of their final internal diameter. The “jacket,” a cylindrical piece of iron, made about 8-100 of an inch smaller than the main barrel, and after having been heated to a degree just below that required to change the color of the metal, iu the language of the forge, to a “black heat,” is then shrunk on. The shrinkage on colling is sufficient to perceptibly decrease the calibre of the shaft or core by compressing the heavy forged steel. All the processes of turning and boring have to be very slowly performed when steel is being worked, and thirty inches a day is the average rate at which a six-inch gun is bored out The first cut is five inches and a quarter, and subsequently rimming out increasing it to near the required diameter. The rifling is done with a shaft constructed in the yards as are nearly all the machines used. Outside the jacket, which extends from the breech about one-third the length of the gun, are placed a number of steel rings passing beyond it, and to about one-half of the total length. These are also shrunk on. All of the surfaces which are thus brought into contact under such a tremendous pressure are carefully ground to as near as possible an absolutely true cylindrical shape, and are, therefore, in actual contract for their whole extent. During all of the handling after the first core is placed in the gun, with the double object of preserving the shape intact and forming a lathe centre. The process of boring and turning the outer surface can be carried on simultaneously by an improved double lathe, in use and manufactured in the yard. The exact cost of each gun is kept, every man’s time being charged to the work lie is actually engaged upon and the cost of the material and handling being also accurately computed. —Ph iladelph ia News.