Page:Popular Science Monthly Volume 88.djvu/446

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��Popular Science Monthly

��A Movable Storehouse Elevator

IN many industries which require the storage and removal of heavy bales, boxes or casks the employment of sta- tionary elevators is impracticable. This is the case in tobacco warehouses, in chemical factories and in storehouses for various raw materials, contained in pack-

���Boxes and bales for storage are easily

handled by two men with this simple

movable elevator

ages half a ton in weight and a cubic yard in bulk, must be handled. As the bales are usually piled up four deep, the ""Nork of storage, if done by hand labor, as very fatiguing.

The Zeitsclirift des Vereins deutscher Jncjenieure says that a movable elevator has been devised by \V. Dahlheim, which has given satisfaction in the establish- ments that have already adopted it. The apparatus consists of a wrought-iron skeleton tower having an inclined front, which forms the runway for the plat- form on which the load is placed. The loaded platform is hoisted by means of a hand-winch, so constructed that the platform remains stationary when the handle is released and descends gently with uniform speed when the handle is pressed backward. There are no separ- ate brakes or catches to operate and ev- ervthing is done with the winch handle. The work is so light that one man can

��raise an average load of 500 pounds to a height of twelve feet in one minute.

The elevator is mounted on two large wheels, at the back, and two small steer- ing wheels in front. When it is to be moved to a distant part of the establish- ment, it is tipped backward on its large wheels and moved like a hand truck. The loaded elevator can be tipped with- out disturbing the load and can be moved through low doorways, while its small width (about thirty inches), allows it to traverse narrow passages. The vertical back of the elevator may be constructed in the form of a ladder, by which the pile of goods can be climbed. The floor of the platform is composed of a smooth iron plate, for bales, or a number of ' small rollers, for boxes. It can be load- ed and unloaded either from the front or the side.

The field of this device is not restrict- ed to storehouses. It may be utilized in the erection of buildings, for loading heavy articles on trucks or railway cars, and in various other ways. Its economy in operation is evident from the fact that for average loads it requires the service of only three men — one to load, one to unload, and one to hoist.

Why Do We Have Two Eyes?

BECAUSE we have two eyes the things we see seem solid and not flat, with the result that we can judge their distance from us with fair correctness. Look through a window at a house across the street with one eye closed and then with the other eye closed. The bars of the win- dow frame will cut across the opposite house in different places. The two fields seen with the eyes separately although in the main alike, differ. When you look at the house with both eyes open the two fields seen by the two eyes are combined and the house across the street assumes depth and relief. Although we see a house with each eye we see only one house with both eyes. This makes the stereoscope possible — an instrument so designed that the two eyes are made to converge on a single point and yet to see two different pictures. If these two pictures repre- sent a chair as it would appear to the right and left eyes respectively, they are perceived as one solid object.

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