Jack felt a curious pleasure in knowing that the Casa Alvarez was in his own district, and would actually be his head-quarters. Hastening down the street towards the walls, he enquired whether the ramparts were manned in force at night in anticipation of attack during the hours of darkness. Tio Jorge informed him that the French had not risked a night attack in force since the beginning of the siege. They continued their mining operations, but they had found it so difficult to make headway above-ground, even in the daylight, that actual assaults and fighting seldom or never occurred between dark and dawn. The ramparts were therefore guarded by a sufficient number of sentries, but not occupied in force, the defenders being only too glad to recruit their overtaxed energies with sleep. When Jack arrived at the wall he found sentries posted at intervals of a few yards. He learnt from Tio Jorge that his command extended from the Santa Engracia convent some fifty yards to the north, where it adjoined the Porta Quemada district under the charge of a personal friend of Palafox, Don Casimir Ulloa. It happened that Don Casimir was making a round of his sentries before leaving for the night, and to him Jack was introduced by Tio Jorge at the point where their commands met. Tio Jorge then took his leave, promising to call at the Casa Alvarez on the way back, and see that a room was arranged for the Señor’s occupation. "Is all quiet to-night, Señor?" asked Jack, after the first compliments had passed. "Yes; nothing has happened since the French blew up a house by the Santa Engracia convent just before dark. But one thing puzzles me, Señor. Do you know this part of the city?" "I was here once before, but that was six years ago, and I was too much a child then to remember it well now." "But you will know that beyond the wall here, which has been greatly strengthened and thickened, the ground slopes steeply down to the River Huerba. You can see it; the water shines in the moonlight. On the other side of the ravine, at the top, are the French trenches." "I see. What puzzles you, Señor?" "I am coming to it. Every night for ten days past I have been at this spot at this hour, and every night I have either seen or heard a French sentry exactly opposite. To-night, however, there is a difference. At dusk we saw the Frenchman tramping up and down behind the trench, just out of range of your good English muskets, Señor; we heard the guard changed; but a few minutes ago, when I looked, I found that the sentry had disappeared. Perhaps my eyes are at fault. Will you look, Señor?"