Moby-Dick, page 359 : This is what I mean. If unmolested, upon rising to the surface, the Sperm Whale will continue there for a period of time exactly uniform with all his other unmolested risings. Say he stays eleven minutes, and jets seventy times, that is, respires seventy breaths; then whenever he rises again, he will be sure to have his seventy breaths over again, to a minute. Now, if after he fetches a few breaths you alarm him, that he sounds, he will be always dodging up again to make good his regular allowance of air. And not till those seventy breaths are told, will he finally go down to stay out his full term below.