Among the most noteworthy automatic machines are the presses which take a continuous roll of paper, print both sides, cut it into leaves, fold these, paste them at the back, and, if desired, sew them together and attach a cover. Such a press stands for the union of several operations once distinct; it argues great ingenuity, careful planning, with paper exactly adapted to the stresses it must encounter, while the ink is of a quick-drying variety.
Dexter feeding mechanism.
Dexter Folder Co., New York.
The Dexter Feeding Mechanism.
Binding operations and a good deal of printing have to deal with separate sheets of paper or card. To feed these to presses, folders or binders was for many years a task for the hand. To-day the Dexter Folder Company, of New York, in a diversity of machines supersedes this toil by an ingenious imitation of manual movements. The uppermost sheet of paper in a pile is for a moment held down at A by a rubber finger, during that moment a small rubber roller B slightly buckles the sheet; at the same time an airblast lifts the sheet from its pile; that done, all in a twinkling, finger A rises and the sheet passes either into a press or a folding machine. So nicely limited is the pathway for the paper that no more than one sheet can pass at a time; if two or more sheets present themselves, the feeding mechanism stops, bringing the press or folder to a standstill. As each sheet passes from under the rubber fingers, the table bearing the pile of paper is lifted by just one thickness of paper.
Self-Acting Appliances in Metallurgy.
Mr. James Douglas, president of the Copper Queen Company, New York, thus describes automatic devices in metallurgy: “The gold mill, with its series of automatic operations, is the offspring of Californian ingenuity. In it manual labor is almost entirely replaced by ocular labor, for superintendence and not work is the function of the mill-hands. The ore, dumped into the breakers, falls into large pockets, whence it slides into automatic feeders, which supply the stamps with regulated quantities. The free gold is partly extracted by liquid mercury in the mortars, and by copper plates attached to their sides, and partly on an apron of amalgamated copper plates, over which crushed pulp flows as it issues from the battery screen. Automatic vanners receive the tailings, separate the sulphurets, and discharge the waste. When the power is water, the stream is divided to Pelton wheels, coupled to the separate groups or even pieces of machinery. The absence of intermediate running gear increases not only the sense, but the reality of automaticity, and makes a skilfully arranged and thoroughly equipped Californian mill one of the triumphs of modern mechanical metallurgy.”
Directive Paths.
An interesting field of ingenuity concerns itself with giving work the right start and a simple path. A tear in a sheet of paper accurately follows the line of a directive crease. Postage stamps, small as they are, we readily detach from one another because perforations give direction to the tearing strain. So the quarryman takes care to cut a V-shaped groove in the rock he is to break, along which groove the break takes its way. A bolt when over-strained will break in the thread, whether this be the smallest section or not, because the thread is a starting point for a parting. A rod of glass is divided with a slight jar, provided that a groove has been filed in its surface. In all this there is shown the importance of avoiding in a casting, or forging, such minute cracks as under severe strain may lead to rupture.