The importance of the safety, and facility of the naviga tion of the Frith of Forth, will best appear by viewing this great estuary as the principal inlet upon the eastern coast of Great Britain, to which ships in the North Sea can fly for refuge in storms of easternly directions. Independent ly, therefore, of this Frith opening the way to so great ex tent of commercial coast from the Red-head in Angusshire, on the north, to St. Abb's-head in Berwickshire, towards the south, with which its shores are bounded ; it is, in fact, a matter of the greatest national importance to open the war, by proper land-marks, for the direction of the mariner to Leith roads, as a safe anchorage at all times of ticl•,and in all states of the weather. For it often happens, when the riding of ships is no longer cafe or practicable in Yar mouth roads, and when the river Humber and Cromarty Frith are inaccessible, the Frith of Forth being now lighted and guarded nearly at all pomth, lies quite open for their reception.
The Liglo-licuse Board, aware of the advantages of the navigation of the Frith of Forth upon general grounds, pro (-ceded to its improvement as their funds would admit ; mid these, not being at first adequate to the much more ex winks of the Bell-rock, cemmenced with the light house of Inchkeith, forming an immediate guide to the roads of Leith. Upon an application bring presented from the Trinity House of Leith, on the 18th :Nlay, 1803, the foundation stone of this useful building was laid, and the light fire exhibited on the evening of the 1st of Septem ber, 1804.
There was no built pier or landing place, nor any road upon the island for the conveyance of heavy materials to the site of the building ; and if any such had existed m the early state of this island, which is indeed more than proba ble, they had been entirely destroyed along with the works of the fortifications, as not the least vestige of these works remained, or could be traced in 1803, when the light-house operations were begun. So completely was this an " un frequented coast," to speak in the language of 1)r John son, that the light-house artificers were actually obliged to lodge in a cavern in the rocks, near the south-eastern part of the island, until they could rear a temporary barrack on the top of the island, near the ruins of the fort.
Hitherto the erections of the Light-house Board had been confined simply to two apartments for one tight-keep er; and, from the infant state of the fund, the first light houses were more of a temporary nature, to answer the immediate purpose of the shipping ; as the whole of the coast of Scotland, excepting the 1:le of May, was in dark ness, or without the aid of light•hous(s, at the commence ment of the institution of the north light-houses. When the works of Inchkeith, however, were undertaken, the funds being in a more prosperous condition, instead of two small apartments for a single light-keeper, the plan of the houses was now extended to the accommodation of a prin cipal and an assistant light-keeper, who now keep a con stant watch, by night, in the light-houses, in the same man ner as is done on ship-board, when a vessel is at sea ; and the whole establishment is now more like the appointment of a public board. The dwelling house at the light-house
stations, instead of exposing, as formerly, a long slated roof on a house of one floor, is now built, as at Inchkeith, with two stories, or floors, and covered with a leaden roof. On the same substantial plan the light-houses are constructed; for instead of the roof of the light-room being framed with timber, and the windows glazed with crown-glass, that of Inchkeith is composed of copper, and the windows are glazed with polished plate glass, of much larger dimen sions; and the whole premises are, in a great measure, rendered fire proof, the floors being all laid with pavement, or flag stones, from the quarries near Arbroath. The build ing operations at Inchkeith were greatly facilitated, and rendered much less expensive, from having the use of the stones of the old fortification and walls, which had been thrown down by an act of the Scottish Parliament. The stones of the old fort had been quarried, and taken from a bed of sand-stone on the island ; and the remains of these old quarries arc still observable, both upon the south-west and eastern sides of the island.
In the original design of Inchkeith light, it was meant to have been built upon the plan of a double or leading light, by the erection of a second light-house, upon the precipi tous rock facing the westward ; and, by keeping both lights in a line, ships were to have been enabled, under night, to pass the narrow channel, between the island of I nelicolm and the dangerous rocks called the Oxcares; but this part of the plan has never been put in execution.
When the present light-house was completed, it was what seamen call a stationary or fixed light, and contained 16 reflectors, made upon the parobolic curve, formed of copper, strongly coated or plated with 511% er, instead of the hollow or cavity of the rdlector being lined with facets of glass, as formerly. Inchkeith light remained as a stationary light till the year 1815, the period when the light of May was altered from an open coal fire to a stationary light, with oil and reflectors ; and it became necessary to alter the character of Inchkeith light from a stationary to a revolving light, agreeably to its present appearance ; and, with this alteration, seven reflectors, instead of the forme number, are now found perfectly sufficient. The machine ry for making the light revolve, consists of a movement or piece of strong clock-work, kept in motion by a weight, and curiously fitted with two governors upon the plan of the steam engine, instead of a fly wheel. The reflectors arc ranged upon a horizontal frame, which is made to re volve, periodically, upon a perpendicular axis, exhibiting, to a distant observer, the alternate effect of light and dark ness, in a very beautiful and simple manner. The reflec tors are brought round in succession to the eye of the ob server, and the angles, or interstices between them, pro duces the effect of darkness, by which this light is distinguished from the light of the Isle of May, and also from the numerous surrounding lights on the opposite shores.