Page:Popular Science Monthly Volume 91.djvu/766

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��Popular Science Monthly

���Alice is pointing to the waxen seal which melts as soon as the heat becomes intense. The melting of the wax re- leases the fire doors, starts the sprinkler system and calls the fire department. At right, the roof of the film stor- age room. The huge ventilators furnish an exit for the cumbusti- ble celluloid fumes

��a tiny wax seal which con- trols the mechanism of each door. The moment the wax is melted the springs release the latches that hold the open doors, and the doors, being mounted on a sloping pul- ley, close by gravity and latch automatically. The closing of any one of the doors makes an electrical contact which turns in a fire alarm.

The sprinkler system is so arranged that the entire outside walls of the build- ing are drenched the moment the water is turned on. Showers also send their con- tents down the ventilators on the roof. A similar sprinkler system sprays the interior of the building, the water being directed so that it falls on the walls and woodwork but not on the films.

��Fire Doors That Close Themselves When the Temperature Rises

IN a certain film storage vault in Culver City, California, highly inflammable motion-picture films worth at times five million dollars are stored. Naturally, the vault is provided with every known protection against fire.

The walls of the building are of special fire brick, plastered on the outside for the sake of appearance. A four-inch layer of asbestos lines the interior, and this in turn is covered with a layer of one quar ter -inch boiler plate. The most inter- esting features of the protec- tive plan are four steel doors which close automatically when an exces- sive heat is reached.

Suppose that a fire breaks out. The heat melts

���How they plow in Porto Rico. The plowing ma- chine is drawn back and forth across the field by two traction engines, one on each side of the furrows

��This Is the Way They Plow in Porto Rico

THE prize for queer ways of plowing a field goes to Porto Rico. In this land of the sugar cane it takes two engines to run a plow, yet the engines do not travel over the plowed ground. The engine seen at the right in the photograph below remains idle, while a similar engine to the left, but not visible in the photograph, is pulling the plowing machine in its direction by means of a steel cable which is shown attached to the lower part of the machine. There are eight plows to the machine, four on an end. When the ma- chine has been pulled all the way across the field the end which now ap- pears in the air willbe lowered to plow the next furrow in the op- posite direction.

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