The Bell rock, or Inch cape, is situated on the north-east coast of
Great Britain, twelve miles south-west from the town of Arbroath, in
Fifeshire, and thirty miles north-east from St. Abb’s head, in the
county of Berwick. It lies in the direct trace of the firth of Tay, and
of a great proportion of the shipping of the firth of Forth, embracing a
very extensive local trade. This estuary is besides the principal inlet
on the northern coast of Britain, in which the shipping of the German
ocean and North sea take refuge when overtaken by easterly storms. At
neap-tides, or at the quadratures of the moon, the Bell rock is scarcely
uncovered at low-water; but in spring-tides, when the ebbs are greatest,
that part of the rock which is exposed to view at low-water, measures
about four hundred and twenty-seven feet in length, by two hundred and
thirty in breadth; and in this low state of the tides, its average
perpendicular hight above the surface of the sea is about four feet.
Beyond the space included in these measurements, at very low tides, a
reef extends about a thousand feet in a south-west direction, from the
higher part of the rock just described; and on this reef the light-house
is erected.
In the erection of a light-house on the Bell rock, independently of its
distance from the main land, a serious difficulty presented itself,
arising from the greater depth of water at which it was necessary to
carry on the operations, than in the case of the Eddystone light-house,
described above, or of any other building of the same kind, ancient or
modern, which had been hitherto undertaken. Its description is as
follows.
The Bell rock light-house, which has not improperly been termed the
Scottish Pharos, is a circular building, the foundation stone of which
is nearly on a level with the surface of the sea at low-water of
ordinary spring-tides; and, consequently, at high-water of these tides
the building is immersed to the hight of about fifteen feet. The first
two, or lowest courses of the masonry, are imbedded, or sunk into the
rock, and the stones of all the courses are curiously dovetailed and
joined with each other, forming one connected mass from the center to
the circumference. The successive courses of the work are also attached
to each other by joggles of stone; and, to prevent the stones from being
lifted up by the force of the sea, while the work was in progress, each
stone of the solid part of the building had two holes bored through it,
entering six inches into the course immediately below, into which oaken
tree-nails, two inches in diameter, were driven, after Mr. Smeaton’s
plan at the Eddystone light-house. The cement used at the Bell rock,
like that at the latter, was a mixture of pozzuolana, earth, lime, and
sand, in equal parts, by measure.
The stones employed in this surprising structure weigh from two tuns to
half a tun each. The ground course measures forty-two feet in diameter,
and the building diminishes as it rises to the top, where the parapet
wall of the light-room has a diameter of thirteen feet only. It is solid
from the ground course to the hight of thirty feet, where the entry door
is placed, the ascent to which is by a kind of rope-ladder, with wooden
steps, hung out at ebb-tide, and taken into the building again when the
water covers the rock; but strangers to this sort of climbing are taken
up in a kind of chair, by a small movable crane projected from the door,
from which a narrow passage leads to a stone staircase thirteen feet in
hight. Here the walls are seven feet thick, but they gradually diminish
from the top of the staircase to the parapet wall of the light-room,
where they measure one foot only in thickness. The upper part of the
building is divided into six apartments for the use of the light-house
keepers, and for containing the light-house stores. The lower, or first
of these floors, contains the water-tanks, fuel, and other bulky
articles; the second, the oil-cisterns, glass, and other light-room
stores; the third is occupied as a kitchen; the fourth is the bed-room;
the fifth, the _library_, or stranger’s room; and the upper apartment
forms the light-room. The floors of the several apartments are of stone,
and the communication from the one to the other is effected by wooden
ladders, except in the case of the light-room, where every article being
fire-proof, the steps are made of iron. In each of the three lower
apartments are two windows; but the upper rooms have four windows each.
The casements of the windows are double, and are glazed with
plate-glass, having besides an outer storm-shutter, or dead-light, of
timber, to defend the glass from the waves and spray of the sea. The
parapet wall of the light-room is six feet in hight, and has a door
leading out to the balcony, or walk, formed by the cornice round the
upper part of the building, which is surrounded by a cast-iron rail,
curiously wrought like net-work. This rail reposes on batts of brass,
and has a massive coping, or top-rail, of the same metal.
The light-room was, with the whole of its apparatus, framed and prepared
at Edinburgh. It is of an octagonal figure, measuring twelve feet
across, and fifteen feet in hight, formed with cast-iron sashes, or
window frames, glazed with large plates of polished glass, measuring
about two feet and six inches, by two feet and a quarter, and the fourth
of an inch in thickness. It is covered with a dome roof of copper,
terminating in a large gilt ball, with a vent-hole in the top. The light
is very powerful, and is readily seen at the distance of seven leagues,
when the atmosphere is clear. It is from oil, with argand burners,
placed in the focus of silver-plated reflectors, measuring two feet over
the lips, the silver surface being hollowed, or wrought to the parabolic
curve. That this splendid light may be the more easily distinguished
from all the other lights on the coast, the reflectors are ranged on a
frame with four faces, or sides, which, by a train of machinery, is made
to revolve on a perpendicular axis once in six minutes. Between the
observer and the reflectors, on two opposite sides of the revolving
frame, shades of red glass are interposed in such a manner, that, during
each entire revolution of the reflectors, two appearances, distinctly
differing from each other, are produced: one is the common _bright
light_ familiar to all; but on the other, or shaded sides, the rays are
tinged of a _red color_. These red and bright lights, in the course of
each revolution, alternate with intervals of darkness, and thus in a
very beautiful and simple manner, characterize this light.
As a further warning to the mariner in foggy weather, two large bells,
each weighing about twelve hundred pounds, are tolled day and night by
the same machinery which moves the lights. As these bells, in moderate
weather, may be heard considerably beyond the limits of the rock,
vessels, by this expedient, get warning to put about, and are thereby
prevented from running on the rock in thick and hazy weather, a disaster
to which ships might otherwise be liable, notwithstanding the erection
of the light-house. The establishment consists of a principal
light-keeper, with three assistants, two of whom are constantly at the
light-house, while the third is stationed at a tower erected at
Arbroath, where he corresponds by signals with the light-keepers at the
rock. This stupendous undertaking is highly creditable to Mr. Stevenson,
the engineer, and does honor to the age in which it has been produced.
The lights were exhibited, for the first time, on the first of February,
1811.