A few months ago I ventured to communicate to the Society, through your hands, some observations on the structure of ancient castles, and the mode of fortifying them; apprehending an enquiry of that nature might possibly have a tendency to illustrate the more early periods of our history, and to fling light upon the relations of many particular events, which are interesting in themselves, but not capable of being fully understood, without some acquaintance with the ancient manners, customs, and arts, that prevailed in those times. The very favourable reception which that attempt met with, induces me now to trouble you still further, with a short account of a single fragment of antiquity, a very extraordinary piece of old Ordnance; which, although it may, at first sight, be deemed an object unworthy the attention of the Society, may perhaps contribute to illustrate some few historical facts, equally with more magnificent and important remains. And I connot help adding, that perhaps the collecting a number of such ancient fragments, of various ages, and preserving faithful accounts of them, may even be a means of furnishing a very useful comment on history.