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To obtain data on the variation of field strength beyond the horizon, simultaneous recordings were made at three locations, one within the optical path of the transmitter, one 700 feet below the line of sight, and one 11,400 feet below the line of sight. All three locations were on the same linefrom the transmitter. Recordings extended over a two-week period, chosen at a time when atmospheric refraction was likely to be favorable. Analysis of the recorded data indicates several things of interest. The variation of field strength at each location was random and showed no correlation with any other location; the range of field-strength variation exceeded 49 decibels at the most remote location; maximum fields generally occurred at night; and previous data on the rate of attenuation beyond the horizon were confirmed.