Bonnet

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In writing this item Engels made use of Marx's excerpts from Burn's A Naval and Military Technical Dictionary of the French Language (London, 1852) which Marx sent him in his letter of September 15, 1857 (see present edition, Vol. 40). These excerpts are extant.

Bonnet, in fortification, a transverse elevation of the parapet, or traverse and parapet, used either to prevent the enemy from seeing the interior of a work from some elevated point, or, in barbette batteries, to protect men and guns from flanking fire. In these latter batteries, the guns firing over the crest of the parapet have to be placed on high traversing platforms, on which the gun-carriage rests, recoils, and is run forward. The men are, therefore, partly exposed to the fire of the enemy while they serve the gun; and flanking or ricocheting fire is especially dangerous, the object to be hit being nearly twice as high as in batteries with embrasures and low gun-carriages. To prevent this, traverses or cross parapets are placed between the guns, and have to be constructed so much higher than the parapet, that they fully cover the gunners while mounted on the platform. This superstructure is continued from the traverse across the whole thickness of the parapet. It confines the sweep of the guns to an angle of from 90° to 120°, if a gun has a bonnet on either side.

Bonnet-à-Prêtre, or Queue d’Hirondelle (swallow tail), in field fortification, is an intrenchment having 2 salient angles, and a reentering angle between them. The latter is always 90°, the 2 salient angles mostly 60°, so that the 2 outer faces, which are longer than the inner ones, diverge to the rear. This work is sometimes used for small bridge heads, or in other situations where the entrance to a defile has to be defended.