...La fig. 25 fait voir, en perspective, cette plate-forme ou plutôt cette enrayure basse, armée. Pour rendre la figure moins confuse, nous avons supposé les clefs pendantes enlevées. On distingue les dix fermes se pénétrant, aux arbalétriers desquels des clefs pendantes vont soutenir les entraits au droit de la portée de chacune des pièces horizontales...

This image comes from Dictionary of French Architecture from 11th to 16th Century (1856) by Eugène Viollet-le-Duc (1814-1879).

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