In lbo big boat shop adjoining the navy yard dry dock a busy gang o: workmen are hard at work learning the rudimenta of a new navy yard industry. They aro trying to make iron niasts, and for amateurs aro succeeding admirably. Up to date such vessels as aro said to compose the United títates navy are sparred throughoul with wood. The new masts are nol intended for uso in the old navy, bul are designed to embellish the new and alleged cmisers now being fashioned by the ingenious Mr. John Roach. The workers in the boat shop have one mast nearly iinished and are framing another. The two are meant for the newly launched cruiscr Atlanta, now duc at the yard. Most peoplfi think an iron mast Is cast and solid, and wonder why its weight doesn't pull it up by the roota or punch a holo in the bottom and slide through. This shows how easy it is to be mistaken. An iron mast is really lighter than wood. A sixty-foot stick of sprnce or yellow pine two feet in diameter at the base weighs far more than the shelHorming the siedern iron steamship masts. These masts for the Atlanta will be fine specimens of their kind. The mammast is two foet in diameter at the base, tapering to seventeen inches at the top, al which point the funnel will bc fashioned square making a marked distinctlon from foreign-made mast heads, which are leit rouud. The main mast is sixty-éight feet four and onehalf inches in length, and the foremast two inches shorter. The method of construction is peculiar. Three T 'shaped rods of steel, the length of the mast to be made, are affixod base outward in circular wooden frames, and around the skeleton thus formed the ready-shaped plates are riveted in Í)lace. The plates are twelve feet in ength and about one-fcalfof an inch in thjekness. They are sold to the Government as steel by a Pennsylvania iirm, but are rather made of first-class iron, or, if steel, of a very mild type, at least so say the mechanics working it. The present forco aro likely to be kept busy long, as all the new vessete ire to be-tlms equipped. Aside from lightness and little danger from breakage, the iron masts have the advantage ot snffering but slightly from cannon shot in wa and will not splinter. Insido strong lateral braces give perfect steadiness, so that no solid shaft would 3e more inflexible. The yard shops are turning outsome ïeavy iron work just now, besides 'raming together the eleven-inch armor plates of the Miautonomah. Mr. Parselü ia laying the floor of the latter craft's gnn deck with sheets of iron three-qnarters of an inch thick and three ind one-half feet wido and twenty'our long, cach woighing three thousand jounds. Years ago a twelve-foot plate was considered the acme in rolled sheets, and so little was it thought that heir length would be increased that a icavy rolling machine whnn put to work in the shop was placed so near the wall as to be unavailable now. A few days ago a rolling machine of mmense proportions arriveil at Iho ¦anl. It will be set up in the new shop n construction next to the Intrepid. ['he three rollers woigh twenty-five ;ons; the two bed rolls scaling eight ons each and the upper one nine - altbgether t fighs fortv-live tons. It vül bc osöd cm the naval destroyers to built in the hereafter, and on the two now being ypain'd. The eoniae ot tlu Dolphin and the Atlanta will bring Bauch continuous work to the vanl, for alter them will ome the Botton, ('biengo and their i-ter-i, eacb with work to do. - Brookyn Eagle. The (MiVcrciicc beiweeti fltttburg and toitüfl ii'ls is lluit the fornicr huvesmuts n their noseg :i tul the latter lmvc snee's.