This paper describes an equipment for the precision measurement of short time intervals as defined by two successive electrical pulses. It features two identically constructed mercury ultrasonic delay lines, one in each of two channels. These lines are precision built and extensible in length by approximately 10%. The measurement is made by first adjusting the lines for equal delay, feeding the pulses into the two channels, respectively, and then noting the extension of the line receiving the prior pulse which is required to bring the two output pulses into coincidence. A continuous range of measurement of 0 to 40 &mgr;sec is available, and the upper limit can be extended as desired by inserting fixed delays in one channel externally. Aside from the continuously variable feature, the instrument is characterized by relatively high precision capabilities, ease of measurement, versatility, and reliability of operation.