INTERVAL. A space of time between two periods. When a person is unable to perform an act at any two given periods, but in the interval he has performed such act, as when a man is found to be insane in the months of January and March, and he enters into a contract or makes a will in the interval, in February, he will be presumed to have been insane at that time; and the onus will lie to show his sanity, on the person who affirms such act. See Lucid interval.