about midnight
The sky , however , was perfectly clear , the stars shone out brilliantly , undimmed by the slightest vapour , while scarcely a breath of wind disturbed the surface of the now slumbering ocean . `` We shall want a breeze to-morrow to carry us to the shore , though I hope it will remain calm as at present until then , '' thought Tom . He very frequently had the greatest difficulty in keeping his eyes open , but he succeeded . He calculated that it was about midnight when he went below , and finding that it was time , roused up Gerald . `` Do not let sleep overtake you , old fellow , '' he said . `` I found it a hard matter to keep my eyes open . '' `` Yes , but mine have been shut for four hours , '' said Desmond .