“The Corporation’s light-vessels are moored with chain-cables of 1¹⁄₂ inch diameter, and a single mushroom anchor of 32 cwt., in which cases the chain-cables are 200 fathoms in length; some of the said vessels are moored to _span-ground_ moorings, consisting of 100 fathoms of chain to each arm, and a mushroom anchor of similar weight at the end of each; a riding cable of 150 fathoms being in such cases attached to the centre ring of the ground chain. The tonnage and general dimensions of the light-vessel are given on the drawing of the lines.” (See Plate XXIX.) ~Beacons and Buoys.~ Still lower in the scale of “signs and marks of the sea,” are Beacons and Buoys, which are used to point out those dangers which, either owing to the difficulty and expense that would attend the placing of more efficient marks to serve by night as well as by day, are necessarily left without lights, or which, from the peculiarity of their position, in passages too intricate for navigation by night, are, in practice, considered to be sufficiently indicated by day-marks alone. Beacons, as being more permanent, are preferred to Buoys; but they are generally placed only on rocks or banks which are dry at some period of the tide. On rocks, in exposed situations, the kind of Beacon used is generally that of squared masonry, secured by numerous joggles (as shewn at Plate XXXII.); and in situations difficult of access, and in which works of uncompleted masonry could not be safely left during the winter season, an open framework of cast-iron pipes, firmly trussed and braced, and secured to the rock with strong _louis-bats_, is preferred. The details of this framework are shewn at Plates XXX. and XXXI. A stone Beacon of the form and dimensions shewn in Plate XXXII., may be erected for about L.700, and the iron Beacon shewn at Plate XXX., for about L.640. In less exposed places, where the bottom is gravel or hard sand, a conical form of Beacon, composed of cast-iron plates, united with flanges and screws, with rust-joints between them, is sometimes used. A Beacon of this kind is shewn at Plate XXXII., which can be erected for about L.400.