Light Beams Guide Blind Thru Building Without Escort (Jul, 1934). "BEAMS of light now guide the sightless through building corridors and up and down stairways. The subject is equipped with a portable photronic cell unit which sounds a buzzer as long as the operator travels along the light beam. The buzzing ceases when the course is changed."
Source: Modern Mechanix http://tinyurl.com/3rd79e _______________________________________________ NetBehaviour mailing list [email protected] http://www.netbehaviour.org/mailman/listinfo/netbehaviour
