Sir, quoth my uncle _Toby_, addressing himself to Dr. _Slop_, --the curtins my brother _Shandy_ mentions here, have nothing to do with bedsteads; --tho’, I know _Du Cange_ says, “That bed-curtains, in all probability, have taken their name from them;” --nor have the hornworks he speaks of, anything in the world to do with the horn-works of cuckoldom: --But the _Curtin_, Sir, is the word we use in fortification, for that part of the wall or rampart which lies between the two bastions and joins them --Besiegers seldom offer to carry on their attacks directly against the curtin, for this reason, because they are so well _flanked_. (’Tis the case of other curtains, quoth Dr. _Slop_, laughing.) However, continued my uncle _Toby_, to make them sure, we generally choose to place ravelins before them, taking care only to extend them beyond the fossé or ditch: ----The common men, who know very little of fortification, confound the ravelin and the half-moon together, --tho’ they are very different things; --not in their figure or construction, for we make them exactly alike, in all points; --for they always consist of two faces, making a salient angle, with the gorges, not straight, but in form of a crescent: ----Where then lies the difference? (quoth my father, a little testily). --In their situations, answered my uncle _Toby_: --For when a ravelin, brother, stands before the curtin, it is a ravelin; and when a ravelin stands before a bastion, then the ravelin is not a ravelin; --it is a half-moon; --a half-moon likewise is a half-moon, and no more, so long as it stands before its bastion; ----but was it to change place, and get before the curtin, --’twould be no longer a half-moon; a half-moon, in that case, is not a half-moon; --’tis no more than a ravelin. ----I think, quoth my father, that the noble science of defence has its weak sides----as well as others.