LIGHTHOUSE, a marine building, erected for the pur pose of exhibiting a light, to warn seamen in the night of their approach to any sand, or insulated ruck: as those on South Foreland, Flamborough Head, the Eddystone, &c. ; or a building erected at the entrance of a harbour, to direct the ingress and egress of vessels during the night, as at namsgate, and other places. The latter kind arc generally smaller than the former, and are called /turbo/D.4/0/s.
Lighthouses are generally built in the form of circular towers, from 50 to 100 feet in height, arched over at the top with a projecting platffirm surrounded by an iron railing. On this plattbrm a framing of stone is fixed higher than the railing, containing an excavation for the reception of the bottom of the lantern ; the space between this frame and the railing, is called the gallery, into which the light-keepers ascend to clean the outside of the glass.
When lighthouses are erected on the main land, there is nothing peculiar in their construction ; in some cases, however, they are required in situations difficult of access, and exposed to the accumulated fury of winds and waves ; and to erect a permanent building on a spot of this descrip tion, requires uncommon resources, and necessarily brings every energy of the architect into action.
The most celebrated antique building of this description was the Pharos of Alexandria in Egypt, the work of Sost•atus of Cnidus, under the patronage of Ptolemy Lagns, and his successor Philadelphus, about 2S3 years before the Christian :era; it is ascertained to have existed for a period of about 1,600 years, and is supposed to have been thrown down by an earthquake. This lighthouse obtained its name from the Island of Pharos, on which it stood ; and ft OM its great celebrity, other structures of a similar kind have frequently obtained the same name ; as the Faro di Messina, and others; but among the moderns, the most remarkable are the Tour de Corduan off the French coast, and the Eddystone Light house, near the coast of Cornwall. The former of these, begun in the reign of Ilenry 11., and finished under I Ienry IV.
in 1010, stands upon a small island near the mouth of the Garonne, in the Bay of Biscay, and w as the work of Luis de Foix, a celebrated French architect. The latter, which has been very justly considered as the chef-d'oeuvre of this species of architecture, was constructed by the celebrated Smeaton ; and still stands an enduring monntnent of his genius. A full description of this remarkable structure has already been given under the article EDDYSTONE 1.1011110IISE.
Among other remarkable buildings of this kind may be noted the Bell-rock lighthouse, off Arbroath, in the mouth of the Frith of Tay.
The reef of rocks on which the Bell-rock lighthouse is founded, is about 427 feet long and 230 feet broad ; at the ordinary height of spring tides it is about 12 feet under water ; and from the floating sea-weed, the ridge can be traced 1,000 feet farther in a direction, when the tides are very low. It is situated on the eastern coast. of Scotland, about It; miles south by east from the fed-head; 12 miles south-east from Arbroath ; 17 miles north by cast from the isle of May ; and 3S miles north by west from Almbs-head. Its geographical position is in 56° 29' of north latitude, and 2' 22' of west longitude. The reef presents an exceedingly rugged and uneven surface. The rock is com posed of red sand-stone, similar to the strata of the contiguous promontory of Ped-head and of the opposite shores of Dunglas in Berwickshire. The present vegetation of the rock consists only of sea-plants ; some of them not of common occurrence on our coast. It is the occasional resting-place of the seal and the cormorant ; and is the chosen residence of numerous marine peones. At the distance of 100 yards, when the tide is low, the water varies from two to three fathoms in depth. The greatest depth between the rock and the opposite shores of Fife is 23 fathoms. This rock, though a mere spot on the surface of the ocean, produces all the remarkable phenomena of in-shore and off-shore tides, which exist on the projecting coasts of the mainland, or among the Scottish islands.