Radio waves may be measured either in length or in frequency: the higher the frequency, the shorter the length of the waves. For example, your WMCA, at the top of the dial, has a frequency of 570 kilocycles, in a wave that has a length of approximately 527 metres. Multiply one by the other and you have about 300,000. WQXR, near the bottom, has a frequency of 1560 kc., and a wave length of approximately 192 metres. These multiplied yield also approximately 300,000 - thereby showing a definite inverse ratio between frequency and length of wave. The ultra-short wave lengths in the light band are measured in millimicrons, or angstrom units. A micron is a millionth part of a metre; a millimicron, a thousandth part of a micron; an angstrom, one-tenth of a millimicron. Red light has a wave length of about 780 M M or 7800 A (angstrom units); yellow, 590 M M or 5900 A; and violet, 390 M M or 3900 A. The range of visibility is thus one octave: from approximately 400 M M to 800 M M. Above that are the ultra-violet rays, and below it, the infra-red. It is also discovered that refraction increases in inverse ratio to the wave length - hence the dispersion of light as it passes through a glass prism. It is a matter of wave length that Mars yields a red light, stimulates the adrenal glands, and thus produces the sundry emotional reactions that astrologists have learned to associate with a Mars accent: and similarly with all the other planetary rays, as distinguished from those of the luminaries.
ASTROLABE ENCYCLOPEDIA
