Electrically Opened Doors

One may be tempted to ask whether it is worth while to. arrange a door o that it wil! open automatically when you step on a mat before it, and will close wften your foot presses another nat beyond, saya the New York Tribune. But, whate:ver opinión may be entertained on this point, the fact that electrical apparatus for thus operating a door has been invented is at least worth recording. A noted lunch-room in Chicago and the city market in Springfield, Mass., have doublé doora equipped in this manner. Over the doorway is placed a suitable box inclosing magnets and machinery. From :his box extends downward a rod, {rom which a horizontal arm reaches along the door. Forces at work within tha box twist the rod and swing the dooi to and fro. When the door is closeri there are some stift springs already coiled up and trying to pull it open. It cannot move, however, until a certain band which is wound up oa & drum has been released. The immediate effect of stepping on the mat is ;o close an electric circuit which frees that band. Then the springs swing the door open. When you step on the oth1er mat another electric circuit is closed, which sets a current flowing through a small electric motor. This puts a drum or spool in motion, winds up the belt and draws the door shut. The motor is more powerful than the springs, so that in closing the door it brings the springs again into a state of tensión sufflcient to do their work over again as soon as a chance occurs. Just before the door reaches a close'd position a switch is automatically moved which shuts off the electric current from the motor. Where this apparatus is applied to doublé doors the outside mat will open the right-hand door, but close the lefttiand one, while the inside mat closes the right-hand door, but opens th luit-hand one.