and saw, with an alarm that it would be difficult to describe, that the wreck had actually sunk into the water several inches within the last few hours.  This was, indeed, menacing their security in a most serious manner, setting a limit to their existence, which rendered all precaution on the subject of food and water useless.  By the calculations of the mate, the wreck could not float more than eight-and-forty hours, should it continue to lose the air at the rate at which it had been hitherto lost.  Bad as all this appeared, things were fated to become much more serious.  The motion of the water quite sensibly increased, lifting the wreck at times in a way greatly to increase the danger of their situation.  The reader will understand this movement did not proceed from the waves of the existing wind, but from what is technically called a ground-swell, or the long, heavy undulations that are left by the tempest that is past, or by some distant gale.  The waves of the present breeze were not very formidable, the reef making a lee; though they might possibly become inconvenient from breaking on the weather side of the wreck, as soon as the drift carried the latter fairly abreast of the passage already mentioned.  But the dangers that proceeded from the heavy ground-swell, which now began to give a considerable motion to the wreck, will best explain itself by narrating the incidents as they occurred.

Harry had left his marks, and had taken his seat on the keel at Rose’s side, impatiently waiting for any turn that Providence might next give to their situation, when a heavy roll of the wreck first attracted his attention to this new circumstance.

“If any one is thirsty,” he observed quietly, “he or she had better drink now, while it may be done.  Two or three more such rolls as this last will wash all the water from our gutters.”

“Wather is a blessed thing,” said Biddy, with a longing expression of the eyes, “and it would be betther to swallow it than to let it be lost.”

“Then drink, for Heaven’s sake, good woman—­it may be the last occasion that will offer.”

“Sure am I that I would not touch a dhrap, while the missus and Miss Rosy was a sufferin’.”

“I have no thirst at all,” answered Rose, sweetly, “and have already taken more water than was good for me, with so little food on my stomach.”

“Eat another morsel of the bread, beloved,” whispered Harry, in a manner so urgent that Rose gratefully complied.  “Drink, Biddy, and we will come and share with you before the water is wasted by this increasing motion.”

Biddy did as desired, and each knelt in turn and took a little of the grateful fluid, leaving about a gill in the gutters for the use of those whose lips might again become parched.

“Wather is a blessed thing,” repeated Biddy, for the twentieth time—­“a blessed, blessed thing is wather!”