The fourth night, supposing the artillery of the besieged to be silenced, they would commence the second parallel, and the fifth night the counter-batteries parallel and perpendicular to the faces to be cannonaded. The sixth night would be occupied with the continuation of the counter-batteries and the commencement, by sap, of the zigzags about as far as one hundred and sixty yards from the crest of the salient angles of the covered way. During the seventh night the construction of the counter-batteries would be finished, and they would dig the demi-parallels. On the eighth night they would continue to advance by sap in zigzag, and arm the demi-parallel with howitzers and mortars, to commence their fire at daybreak at the same time as the counter-batteries. On the ninth night the sap-fronts would reach the glacis fifty or sixty yards from the salient angles of the covered way, and the zigzags would enter the third parallel, which they would continue by day. On the tenth night the works would be completed, the third parallel should be finished, and batteries of stone mortars planted there. On the eleventh night they were to drive two saps a length of twenty-six or thirty yards, right and left, of the capital (Fig. 71). They would dig the circular trenches, and then advance straight on the capital by double sap to within range of hand-grenades; twenty-six to thirty yards from the salient of the _places d'armes_. Protected by the fire of the third parallel, this work would be continued by day. The twelfth night would be employed in tracing the trench cavalier by means of two saps; these works were to be terminated by day. The thirteenth night, starting from the extremities of the trench cavaliers near the capitals, by double sap, they would crown the salient angles of the covered way. At daybreak these crownings would be finished, and the construction of the counter-batteries commenced. They would get down by means of two saps (Fig. 71) to the _place d'armes_, to establish a lodgment parallel to the rounding of the ditches. If necessary, they would drive right and left of the crowning two saps which would meet each other in the middle of this crowning. A fourth parallel would, if necessary, be established, on which they would then place the stone mortars of the third parallel. If this fourth parallel was not needed, they would advance from the third parallel by means of a double sap directly upon the salient of the re-entering _place d'armes_. The fourteenth night the crowning was to be extended along the branches of the covered way as far as the first traverse. The construction of the counter-batteries, and that of the fourth parallel, would be continued. If this fourth parallel were not required, the saps would reach to the salient of the re-entering _place d'armes_, which they would crown. At daybreak the breach batteries would be commenced.