Vision by Radio - Early Television Foundation

of inches between lens and plate.For example, thelens in Washington and its photographic plate inBoston; with this exception, that the one lens inWashington can put a negative on one, ten or onehundred photographic plates in as many differentcities at the same time, and at distances limitedonly by the power of the broadcasting station, radioinstead of light carrying the image from lens to plate.The time for transmitting a picture depends uponthe size of the picture and strength of light, say,from three to six minutes, using a filament lamp as asource.The radio photograph receiving instruments arerather simple and inexpensive and, like a loudspeaker,can be attached to any standard amplifying audioradioreceiving set.FILAMENT LAMP:For the light source for radio photographs a filament lamp is employed, and in a single turn coilenclosed in a hydrogen atmosphere.This miniaturefilament coil is imaged on a photo negative plate,and the variation in the light is caused by puttingthe incoming radio signals through this lamp, perhaps after the filament has been brought to a redglow by a battery current. By adjusting the speedof the motor to the temperature change of thisfilament soft gradations of light and shade areobtained which probably can never be equaled byany other device, a photograph of true photographicvalue, entirely free of lines.The author wishes to take this occasion to expresshis appreciation of the splendid assistance of theGeneral Electric Company, under the personalsupervision and hearty cooperation of Mr. L. C.Porter, who from the very first has shown his con-28