Drawing Twenty Shades at Once 



The stereopticon operator pushes a button 

 and presto! the shades are raised or lowered 



A simple push of a button by the stereopticon operator and all the shades in 

 the auditorium are lowered simultaneously. Another push and they are raised 



THE inconvenience of having to draw 

 each window shade separately in an 

 assembly room when motion pic- 

 tures or stereopticon views are to be shown, 

 has been overcome by an electrical de- 

 vice, which makes it possible to draw all 

 the shades simultaneously by simply 

 pushing a button. This new device is 

 installed in the auditorium of the Bureau 

 of Standards building, Washington, D. C, 

 and is manipulated by 

 the motion picture or 

 stereopticon operator. 



Two horizontal shafts 

 extend on each side the 

 full length of the room 

 within the wall, directly 

 over the window frames. 

 Each shaft is revolved by 

 means of a small electric 

 motor, placed in a pocket 

 in the wall just outside of 

 the auditorium, as shown 

 in the accompanying il- 

 lustration. A special 



Motor outside 

 of room 



, 'Limit 

 5witch 



Wires in conduits to 

 limit -switches 



Details of the limit switch which 

 opens and closes the circuits 



switch is installed near the motion-picture 

 projector, by means of which the operator 

 can easily turn the shaft in either 

 direction, so as to raise or lower the shades. 

 Power is transferred from the motor 

 shafts to the shades by means of gears 

 on the shafts, which mesh with smaller 

 gears mounted on one end of each roller. 

 A limit switch controlled 

 by the operator's main 

 switch, breaks the cir- 

 cuit when the curtain 

 has been pushed down 

 to its lowest or up to its 

 topmost position. The 

 direction of revolution of 

 the motor shaft is con- 

 trolled by the operator's 

 switch, and the gear on 

 the motor shaft drives 

 that on the end of the 

 roller, as shown. The 

 revolution of the motor 

 shaft causes the threaded 

 nut around the motor 



274 



