midnight
Moreover the water supply of the little party was almost exhausted and without water they faced a terrible death . Because of the unknown dangers which , it was felt , surrounded them it was decided to set a watch that night and keep the fire burning through the dark hours . Harry and Ben were to share the first watch and Frank and Billy agreed to take the second one . Nothing had occurred when Ben , at midnight , aroused Frank and the young reporter and told them it was time to go on duty . The boys had been on sentry duty for perhaps an hour with nothing but the lapping of the waves against the shore of the floating island to break the deep stillness , when suddenly both were startled by a strange and terrible cry that rang through the forest . With beating hearts they leaped to their feet and strained their ears to see if they could ascertain the origin of the uncanny cry , but they heard nothing more . Hardly had they resumed their places by the fire , however , before the wild screams rang out again .