Upon the following day they took their post again at the window, and after some hours watching saw three bolts fired from the next window. Watching intently, they saw the two first fall into the moat. They could not see where the other fell; but as there was no splash in the water, they concluded that it had fallen beyond it, and in a minute they saw a soldier again advance from the battery, pick up something at the edge of the water, raise his arm, and retire. That evening when Captain Vere returned from the ramparts they informed him of what they had observed. "Doubtless it is an act of treachery," he said, "and this merchant is communicating with the enemy. At the same time what you have seen, although convincing evidence to me, is scarce enough for me to denounce him. Doubtless he does not write these letters until he is ready to fire them off, and were he arrested in his house or on his way to the warehouse we might fail to find proofs of his guilt, and naught but ill-feeling would be caused among his friends. No, whatever we do we must do cautiously. Have you thought of any plan by which we might catch him in the act?" "If two or three men could be introduced into his warehouse, and concealed in the room from which he fires, they might succeed in catching him in the act, Captain Vere; but the room may be an empty one without any place whatever where they could be hidden, and unless they were actually in the room they would be of little good, for he would have time, if he heard footsteps, to thrust any letter he may have written into his mouth, and so destroy it before it could be seized." "That is so," Captain Vere agreed. "The matter seems a difficult one, and yet it is of the greatest importance to hinder communications with the Spaniards. To-night all the soldiers who can be spared, aided by all the citizens able to use matlock and pick, are to set to work to begin to raise a half-moon round the windmill behind the point they are attacking, so as to have a second line to fall back upon when the wall gives way, which it will do ere long, for it is sorely shaken and battered. It is most important to keep this from the knowledge of the Spaniards. Now, lads, you have shown your keenness by taking notice of what is going on, see if you cannot go further, and hit upon some plan of catching this traitor at his work. If before night we can think of no scheme, I must go to the governor and tell him frankly that we have suspicions of treachery, though we cannot prove them, and ask him, in order to prevent the possibility of our plans being communicated to the enemy, to place some troops in all the warehouses along that line, so that none can shoot therefrom any message to the Spaniards." Just as Captain Vere finished his supper, the boys came into the room again.