Phenomena usually thought of as being affected by solar activity are: Sun spots, solar constant, earth's magnetic field, atmospheric electricity, auroras, earth currents, and, as has been recently shown, radio transmission. In order to correlate these with each other, the daily character of each must be reduced to some single figure. The factors which lend themselves most easily to quantitative correlation are sun spots, solar constant, earth's magnetic field, daylight radio transmission and night radio transmission. For sun spots, the numbers as prepared by Wolfer are used and for variations in the solar constant, the measurements by Dr. Abbot. Several sets of character figures of the earth's magnetic field were available. Of these, the three figures show too great a contrast between disturbed and undisturbed conditions while the Van Dijk show too little. A set of figures which showed a contrast between the disturbed and undisturbed conditions of the same order of magnitude as that obtained between disturbed and undisturbed radio conditions was devised. This method consisted of obtaining from the hourly averages, the total variation of the horizontal and vertical components of the earth's field. Such a figure is easily computed although better results might be obtained if the variation were taken directly from the magnetogram. The diurnal characteristic of long wave transatlantic radio transmission can be divided into four parts: daylight over entire transmission path, darkness over entire path, and the sunset and sunrise transition periods.
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Sep 1, 1929
C.N Anderson 
