Zinc, in its best application, makes steel wire weatherproof for many years and the apparently simple process of galvanizing, the fixing of a coating of zinc on the steel has multiplied many fold the utility of steel wire in places where it could ill be spared. But there is galvanizing and "galvanizing." The first is worth the money it costs. There are other coated wires, too. The aeroplane strands and cords are tinned. There is a bronze enamel, and a copper coating which looks as if it were applied for protection but is really the incidental result of a dip in sulphate of copper, for other purposes in the course of fabrication. The coating of wires is chiefly done in the wire works of the Kinkora Mills, though a galvanizing house is maintained also at the Upper Works. For wire that is to be made into galvanized ropes and cords, the galvanic treatment is given before it goes to be made up. [Sidenote: JOURNEYING THROUGH THE ROEBLING PLANTS] For exercise, a journey through any one of the Roebling plants, and especially the great Upper Works, is as good as thirty-six holes of golf. It is upstairs and downstairs, over an interminable number of thousands of square feet, through the mazes of a picture that is always changing its detail and its rate of speed, but which is all centered on one idea, to keep the stream of wire and wire rope, of all sizes, kinds and colors, moving toward the shipping room. It all seems so easy in its progress, so free from friction or any trace of confusion, that the layman does not stop to consider how many problems have bobbed up along the way of production, even of the most modest wires and rope. Wire is a trade involving intimate knowledge of many lines of business and manufacture, since the character of wire required differs in nearly all. [Illustration: HOISTING FULLY COMPLETED LOCOMOTIVE WITH WIRE ROPE SLING] To the novice, wire is wire. Here he learns that what is wire for one thing is valueless for another and wire that looks to the unpracticed eye as if it were ready for market always has to undergo a few more processes before it is up to demands. Wherever, however far, you travel in this succession of high-roofed, airy buildings, you come always upon some new regiment of machines, some new container of chemical or metal, with a long line of reels unwinding wire to undergo some additional treatment. And always moving among the buildings are cars, big and little, packing wire or material from one place to another, to feed the wheels and furnaces. The tonnage from plant to plant and from house to house in the Roebling works would make a first-class annual business for many a modest railroad, even if it carried nothing else. [Sidenote: INSULATION]