Electro-Pneumatic Protector, An Italian Diving Bell—The Inventor Writing Letter at the bottom of the sea, and more

1871 Scientific American  
We illustrate, in the accompanying engraving, a very unique invention, which, so far as we can at present see, ap pears to afford absolute protection to safes or vaults to which it is applied; and it does this without necessitating great strength in the walls of such safes or vaults, and the conse· quent expense attending their construction. It has been shown that burglars have been able to keep pace with the inventions, that have sought to defeat them by sheer strength of brute material,
more » ... where a large ex pense is incurred to so pile plate upon plate, and to temper and harden, till the time necessary to penetrate these com bined obstacles is NEW YORK, NOVEMBER 11, 1871. suitable supports on the inside of the door where it is hung when not in use, in our engraving. A mercury gage is also shown on the door, which indicates at all times whether the exhaustion is complete or not. On the inside of the door, in any convenient position, is per manently attached a wedge of copper. This wedge is shown at the middle of the top of the door in our engraving. When the door is closed, this wedge is forced in between the ends of two strips of copper, establishing an electric circuit be tween the protector case and the alarm apparatus, which is shown in our engraving, attached to the front of the building in which the safe is placed.
doi:10.1038/scientificamerican11111871-303 fatcat:xcuwsaxz7ndnrh4dtnvdat6yai