750 



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. 



