THE ELECTRIC EYE

Evening Post, Volume CVII, Issue 102, 4 May 1929, Page 18

THE ELECTRIC EYE

Tlierc is a thing that is too wonderful and diflicult, for us to understand, but perhaps wl; can try to. Prom New York to England the Marconi beam system of wireless lms Hashed across images of drawings and the printed and written word with the speed of light. It is the electric eye which sees them first and helps the common human eye to see them again. By the electric eye we mean that photo-electric cell which is so sensitive to light that when a ray falls on it the cell transmits an electric current. When the light is shut off the current stops. In New York a printed telegram, a written worß, or a drawing, is placed in position on a revolving cylinder. A beam of light narrowed down to a needle-point of brightness is then made to trace out every bit of the drawing or the writing. As the spot moves it is reflected from the sheet of paper and its picture lines or its letters, and sometimes the reflection will be bright and sometimes dull. These reflections pass into the electric eye, and that very sensitive eye records the differences of lightness and darkness, semi-darkness and dullness, as eicctrie current.

The cylinder, with the picture or print attached to it, is always moving at a speed that is known. So is the xxrintcd finger of light. Everything is exact; it has taken two years of experiment to make it so.

The currents delivered by tho electric eye are magnified, and are then sent across the Atlantic by beam wireless. When these electric impulses arrive at Sonierton, the process is reversed. The currents are sent backward. The roceiving electric cell acts in a different way from its twin in New York. It winks. It allows the spot of light to shine only when the current conies through.

But in England the receiving cylinder, on -which a strip of photographic paper is fixed, moves exactly in time with the cylinder at New York. The spot of light which traced"the drawing at New York- and the spot of light which traces it again on the photographic film keep time and tune. Thus the moving fingers of light move in unison, they writo and draw together; and thus the picture in New lork appears simultaneously 3000 miles away. Is it not a miracle?