Fig. 50 A gives the plan of one of these towers at the level of the lower battery, and B its section through _a_, _b_.
These towers were forty yards in diameter on the outside, and consisted of a low battery, whose floor was six feet beneath the upper level of the plateau. The descent to this low battery was by a slope ending in an octagonal hall whose vaults rested on four great cylindrical pillars. Three chambers with embrasures for three large cannons opened into this hall. By the galleries, C, there was a communication between two of these chambers and two other smaller ones pierced with embrasures for culverins. From the descent D, two passages, E, gave access to two chambers, F, likewise arranged with embrasures to receive two large guns.
[Illustration: FIG. 50.--MASONRY TOWER FOR ARTILLERY.]
The barrel vaults of these rooms had openings to allow the smoke to escape. Small powder magazines, G, opened near each of the chambers, and five large lunettes pierced in the vaults of the central hall gave air and light to the interior. At H, a well was connected with a cistern constructed under the central hall, as indicated in section B. This cistern was supplied by rain-water falling on the platform and discharged by four pipes passing down through the inner walls. Two winding staircases connected the lower battery with the platform and the curtains of the fourteenth century, I I, and allowed of a descent through two posterns, K, into the braie, L, defended by an epaulement, a palisade, and narrow ditch. Flanks, _l_, raked the salient of this braie. The curtain, whose rampart walk rose six feet above the level of the platform, closed the gorge of the tower, as shown in section B at N. Two watch-towers, P, were built in the thickness of the parapet, pierced with nineteen embrasures for small pieces. This parapet was not too high for arbalisters to shoot over its slope. A wide incline, R, facilitated the getting up of guns and the ascent of men to the platform.
Fig. 51 presents a bird's-eye view of boulevard _I_,[36] with the ramparts of the fourteenth century. These boulevards were earthworks, and their interior surface was four yards below the level of the plateau. The boulevards, B and C, raised at the western angles of the castle, had their platforms on a level with the bottom of the ditch, as mentioned above. Having thus described the general plan and the details, we proceed to narrate the events of which the town of La Roche-Pont was the theatre in 1477 and 1478.