1. In refraction work, the additional time required to traverse a raypath over the time that would be required to traverse the horizontal component at the highest velocity encountered on the raypath. Compare intercept time. See Sheriff and Geldart (1995, 439). The concept implies that the refractor is nearly horizontal under both source point and detectors. Delay time is often assigned separately to the source and geophone ends of a raypath. See Figure D-4. 2. Delay produced by a filter; see filter correction. 3. Time lag introduced by a delay cap. 4. In induced-polarization work, the time interval between the ‘‘off’’ instant of the charging current and the instant a measuring voltmeter oscillograph is turned ‘‘on.’’ Delay times up to 500 or 1000 ms may be necessary to allow dissipation of transient voltages that are not related directly to the polarization decay voltage.