The Coconino weekly sun., 1894-05-17

American production and manufac, ture. Therefore in the creation of a gun forging, it is necessary that if must be of the best steel in America compounded exclusively of American materials. This forging must be of the finest open-hearth gun steel and the casting must weigh about double what the forging that is to be made from it will weigh. If there are any bubbles, or any flaws or rifts what. ever, in the steel it will be rejected by the gun foundry and turned back t1 the producer of it. The forging is made into shape approximating that ot the finished gun, so that it is all ready for manufacture when it reaches the gun foundry.
 Of all of the processes which are gone through with at the navy yard gun foundry in the manufacture of large cannon. the preparation and placing of a jacket is the most interesting. The jacket is large cylinder placed over the original tube at the rear, and con- passing the powder chamber to give it greater resistant strength. The jacket forging Is bored up from the in- side to diameter slightly less than Shc exterior diameter of the tube which it is to cncircle. The jacket is then expanded by heat in hot air fuT~ mace, and, lifted carefully by means of a crane, is placed directly above the original tube which is perpendicular and securely held with the breech up- ward. The jacket is not only heated to a white heat, but to an almost inn pcrceptible dull red. It is allowed to descend from the crane accurately and to slip down over the breech end of the tube, the expansion of the heated metal of the jacket making this move ment possible, notwithstanding the fact that the inner diameter of the jack ct is somewhat less than the outside diameter of the tube when the jacket is cool. This process of putting on the jacket is one of the most remarkable pieces of skilled work that can be done with machinery. When the jacket is finally lowered into it's place over the rear of the original tube, the jacket fits tightly over the tube and com presses it as it becomes cool. By this operation the tube and jacket are prac- tically combined into one piece.
 There are four hoops also bored out to diameter slightly less than the re- spective portions of the gun which they are intended to encirclc, and one after another they are put in place by the same process as that used in jack eting, the metal cooling and contract ing, and eompressing the inner layers firmly in it's embrace. The great can non is thus thoroughly reinforced and then the work of rifling and finishing begins. The first thing to be done when all the jackets and hoops are on is to take the gun from its upright position, put it on a lathe and have it turned down over its whole inside to its completion. When you remember that each one of these guns weighs sixty-five tons, you will realize that the mechanism in the gun foundry which picks up and lays down and moves around these immense bodies of steel must be an approximation of per- lection. This work is only rendered possible by reason of the fact that the gun foundry contains eight prodigious gun lathes of unique design and un- limited power; and that the lifting power of the crane is limited only by the horsepower of the steam engines. One of the immense lathes in the gun foundry has capacity for boring guns fifty-one feet in length and of turning tubes of fifty-seven feet, and conse- quently could bore guns of sixteen inch caliber.
 It is interesting to see one of the great cranes travelling from one end of the big shop to the other, noiselessly, smoothly stretching from one side of the ceiling to the other, its little wheels well oiled and not a sound 10 be heard save when the clanking chains are let down to encircle some heavy object. The man who stands in the crane, and is it's engineer and di- rector, is so high in the air that he looks like a mere boy. While it may be true that the hundreds of men be- low who are rifling, polishing, finish ing and perfecting the great gun may be more scientific, and their work may be more important, nevertheless, when you visit the big foundry, you will carry away with you a more distinct memory of the man in the crane than of all the other wonders of the place.
 SMITH D. FEY>