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Show Radio Makes Maps for Ships on Briny Deep "I'SU'I!," familiar key letters to every ev-ery radio operator on the high seas, indicating I'niled Slates weather bulletins, bul-letins, may soon pass out of hearing. It is now poss.ble for whole weather maps io he broadcast from Washing-Ion Washing-Ion to ships at sea and be drawn accurately ac-curately by a radio-mechanical apparatus appa-ratus on board each ship equipped to receive them. Experimental work between be-tween the naval broadcast station at Arlington and the warships Kittery and Trenton have proved that the new met hod is practicable. No longer do radio messages have to be transcribed fiom dot-dash code into writing and from that to a blank map. The whole process can now be done by radio and in- n ad at a glance. A map to be broadcast Is printed on an S by 10-inch sheet of photographic mm. the negative Is used for actual i t-ensmission. The map received on shipboard Is of the same size. The : ransniission method is much the same as that now used to send pictures by icdio. The negative Is wrapped around a ss cylinder which revolves at a unl-:'or::i unl-:'or::i speed. A ray of light from within with-in penetrates the film whenever it , to--sos one of the lines drawn on the ap and actuates a sensitive photo-e!e photo-e!e trie cell. Each momentary dicker o" light decreases the resistance of the ilium sulphide cell and a slight .. .re (,f current passes through. These s -:i -is lire amplified and broadcast on v.":o meters as an irregular series of :o's and dashes which have been ,con-"'ng ,con-"'ng ship radio operators of late w ho have tried in vain to decode them, not i:r it 'standing what they were. The receiving apparatus operates as t'.oes lie sending mechanism, hut in reverse order, tin ally actuating a pen v l.ie'i inscribes the transmitted map on the sheet of paper wrapped around a revolving cylinder. Thus the whole job is done and each ship has its daily weather map an S by Pi sheet of incalculable in-calculable value to navigation. |
