The Type 916-AL Radio-Frequency Bridge is a null instrument for use in measuring impedance at frequencies from 50 kc to 5 Me. The low-frequency limit is mainly determined by sensitivity considerations and in most cases measurements can be made with slightly decreased accuracy at frequencies as low as 15 kc. Measurements can also be made at frequencies somewhat above the nominal upper limit with decreased accuracy and sensitivity. The bridge is used with a series-substitution method for measuring an unknown impedance, Zx, in terms of its series resistance component, Rx, and series reactance component, Xx. The resistance is read from a variable-capacitor dial directly calibrated in resistance (in ohms). The reactance is read from two variable-capacitor dials directly calibrated in reactance at 100 kc. The resistance dial reading is independent of frequency. The readings of the reactance dials increase linearly with frequency. For frequencies other than 100 kc the reactance dial readings must therefore be divided by the operating frequency in hundreds of kilocycles. The resistance dial reads from 0 to 1000S2; the main reactance dial from 0 to 11,000ft; and the incremental reactance dial from 0 to 100ft at 100 kc.