"Don't answer, boy," said Sir Edward softly. "But father!--if--" "It is only a boast. They dare not do such a thing as that. Come." They retired, making for the mouth of the cavern, where the cool night air blew with refreshing force. "But we cannot give up, father," cried Mark. "I am not going to give up, my boy," said Sir Edward quietly. "When an assault upon a stronghold fails, a general tries to starve his enemy into submission. We must do the same here. Unfortunately they must have stores, and they have a good supply of water from a spring within there. But still we must try. The first thing is to protect ourselves from a sudden attack, and this will be easy. Now, my lads, every man take in a block of stone, and carry it into the cavern as far as the end of the first chamber. Take these from the breastwork; we do not want it now, for we shall encamp inside." Mark nodded approval, and the men, glad that the night's fighting was at an end, set to work with a will, after laying their arms aside; and in less than an hour had walled up to a great thickness the narrow exit from the cavern, wedging in the top stones with blows, and in spite of the want of mortar producing a good solid piece of work, through which no pikes could be thrust. This done, Sir Edward reduced his force to one-third, this being plenty to defend the wall should it be attacked from the inner side; and the rest were sent back to the Tor Castle, for provisions and blankets. "Now, Mark, lad," said Sir Edward, "the thing to consider is, how long can the enemy hold out?" "Not long, father," replied the lad; "they cannot have a very good supply." "That," said Sir Edward, "remains to be proved." CHAPTER TWENTY SEVEN. PREPARATIONS FOR A SIEGE. Siege was now commenced, Ergles being to all intents and purposes an impregnable natural castle. Provisions and other necessaries were brought up, and the force was divided into three watches, who regularly mounted guard in the chamber in front of the wall. But the whole of the next day passed without a sound being heard, the enemy not attempting to break down their own side, for fear of getting into a trap, the utter stillness being interpreted to mean a _ruse_ to get them to make an opening through which an attack would be made. Then another day was passed, and still all was quiet; but toward the middle of the next those on guard in the chamber heard, and reported to Mark, that they could hear the distant sound of stones rolling down, and Mark went and listened so as to determine whether his father ought to be roused, for after a very long watch he had lain down upon a blanket to sleep. "I wouldn't call un, Master Mark," said Dan. "He's tired enough. Watches twice to our once. Let the hounds come; we could account for 'em if they tried to pull our wall down."