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Experiments with high-speed boats at Gloucester, Mass, in 1910-12, resulted in sustained governmental interest in radiodynamic torpedoes from 1912 to 1931. This culminated in the successful radio control of the course of a modified standard naval torpedo throughout a 9000 yard run at an operating depth of 12 feet. Many developments by the Hammond Laboratory established basic principles used in modern airborne guided missiles, including the stabilizing, security, bat, proximity, and homing principles. Needs for improved devices and circuitries for control purposes stimulated the early development of principles used in modern communications. The Hammond Laboratory sponsored the first nondetector applications of the filamentary type triode for linear amplification and for transmitter and heterodyne purposes in 1911-12. The intermediate frequency principle for selectivity purposes was developed in 1912, stemming from the heterodyne principle of Fessenden and the two-channel security principle of Tesla. At a conference at Gloucester in October, 1912, disclosure of these developments led immediately to the Alexanderson development of the tuned radio frequency principle and to the accelerated development of the high-vacuum triode by Langmuir and White. The first military application of the intermediate-frequency principle was to the solution of a World War I problem of mitigating the interference of enemy spark type transmitters upon communications from front line infantry. The receiver of the system was structurally of the most general superheterodyne type for continuous-wave reception.