David let the bit of paper blow overside and slipped into the chart room to calculate the position of the _Hanoverian_. The chart showed him that she was a hundred and fifty miles west and considerably to the southward of the _Roanoke_ when the message was sent. When David returned to the deck an officer was already making reports of the temperature of the water, and Captain Thrasher was standing with head cocked and a hand at his ear, listening, on the chance that the clamor of the fog-whistle might fling back a telltale echo from some hidden mountain of ice that lay in ambush.