Note 35 — CHAPTER 7 THE DISCOVERY OF WIRELESS TELEGRAPHY

When all the atoms and molecules of a substance vibrate in one plane, e. g., as the plane of a train of waves would be if drawn on this page, the wave is said to be polarized. Ordinarily, light-rays are sent out from particles vibrating in different planes; they may be vertical or horizontal, or diagonal, or they may move in a curved path—circles or ellipses. Ordinary light-vibrations are mixed up together, vibrating in all planes, and special devices—“polarizers”—are required in order to separate any one particular vibration from the rest.