The captain no longer interfered in any way with the actions of his young guests. They were entirely free to do as they pleased on the ship, and apparently were under no surveillance. As they came on deck on the fourth morning at sea, the day was beautifully bright and clear. The sky was taking on that peculiar blue that is seen only in the lower latitudes. The atmosphere seemed to have thinned, and the horizon to have moved away a mile or two. The sea was as smooth as glass and the steamer was ploughing her way along at the rate of fifteen knots (miles) an hour. As usual, the decks were deserted, with the exception of the man at the wheel and the two lookouts who were always on post, day and night, no matter how clear the day, or how unnecessary the double watch might seem.