Page:Popular Science Monthly Volume 89.djvu/253

 The Burijflar-Proof Store- Window

���Let the burglar break the g!ass ami at once a curtain of steel is released from the top of the window. It drops of its own weight the instant the glass is broken and one or more of the wires in back of the window are fevered. The curtain is prevented from falling when the window is being cleaned by a simple safety appliance. A sprocket wheel winds up the cur- tain in a "set" position on the shaft. The breaking of one wire will drop the curtain

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