CARR ROCK BEACON as executed in the year 1821.
Drawn by J. Slight
Engd. by E. Mitchell
PLATE II.
Pl. II.
The Carr Rock Beacon is represented in Plate II. and referred to in the introduction at page [53]. The diagram marked Figure 1. is an outline of the rock, shewing the position of the beacon, and plan of the first course of the building, made to a radius of nine feet, cut in a dove-tailed form, after the manner of the courses of the Edystone and Bell Rock Light-houses.
Figure 2. is a section of the rock on the line A, B, Fig. 1. with a perpendicular section also of a tower of masonry and apparatus, for tolling an alarm-bell, which was originally intended for this situation. In Fig. 2. letter a represents an aperture measuring 3 inches in diameter, which was perforated with much labour and care through a block of granite 7 feet in length, previously to its being laid. This canal was intended to admit the tidal-waters into the interior chamber of the building marked b, in which the flood-tide was to act upon an air-tight copper-tank, marked c, and its rod of connection formed into a rack with teeth, by which motion was to be given to a train of machinery, represented at d in the void of the building. The machine was to act on the vertical shaft e, connected with a series of hammers f, placed under the great bell g, which was to have measured 5 feet in diameter, and become the cupola or roof of the building. In this manner the bell was to be tolled to forewarn the mariner of his approach to the dangers of the Carr, and the other extensive ledges of sunken rocks in its neighbourhood. By the rise of the flood-tide, and consequent admission of the waters into the canal a, the tank c, with its connecting rod, not only lifted the bell-hammers f, and, at the same time, also elevated the weight marked h, which, in its descent during ebb-tide, was to have continued the motion of the machinery; and thus, by the alternate operation of the tides, the continual tolling of the Bell was to have been preserved.
It will further be seen from the section of this building, that the masonry of the solid is connected perpendicularly by means of stone-joggles inserted half into the one course and half into the other. But in the void or upper part, instead of the joggles, the bed-joints of the stones were let or sunk about an inch in depth, into each other, as at the Bell Rock, forming so many bands or girths to the work. This will be observed by narrowly examining the section at letter i, with its accompanying diagram Fig. 3., which represents a plan of one of the courses of the void, shewing how the stones were connected horizontally by a system of dove-tailing, as is further represented in Fig. 4., being a plan of a course at the level a, k, in which the perforation is delineated for the admission of the tidal-waters.
The ascent to this building was to have been by means of a ladder of cast-iron or flight of steps, marked a, i, l, fixed on the outward wall by means of screw-bolts fixed into brass-bats, sunk into the masonry, and run up with lead. The entrance-door of this building was formed in the cast-iron frame or pedestal on which the great bell was to have been supported, the access to the interior being by the balcony, round which a cast-iron rail was intended, not only for the safety of the keepers or occasional attendants, but also, in some measure, to defend the bell from the sprays of the sea.