That her capacity including her machinery shall be sufficient to hold provisions for Six persons to continue at Sea for twenty days;
Third
That Six persons can enter such a vessel & descend in her under water at pleasure,
Fourth
That the Six men can continue under water three hours without renewing the air,
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Fifth
That to renew the air, it is not necessary the Vessel should appear above water; but approaching the Surface two tubes project, through one of which the mephitic air is discharged, through the other fresh air is drawn into the Vessel, which operation can be performed in 3 or 4 minuets, to continue again three hours under water; in this manner a crew can conseal themselves under water during the day, on renewing the air 4 times, hence might lie many days in the Neighbourhood of an enemy unperceived,