An Account of the Bell Rock Light-House / Including the Details of the Erection and Peculiar Structure of That Edifice; to Which Is Prefixed a Historical View of the Institution and Progress of the Northern Light-Houses

by Robert Stevenson

Fig. 1. represents part of the outward wall A A A A, and entrance-door, one leaf or half of which is open, and the other shut; a, one of the handles for opening and shutting it, connected with a thumb-latch; b b the bolts for securing the door when shut; c c c c the hinges; d d d d the brass guard-plates at top and bottom of the door, for defending the timber. The door is framed of fir-wood, and measures 6 feet 4 inches in height in the clear, besides the brass-checks upon which it shuts at top and bottom, which are of 2 inches in depth, as shewn at e in Fig. 1., and also by an end view in Fig. 2. The two leaves form a common breadth of 2 feet 10 inches in the clear. A cornice of brass is formed on the lintel of the door answerable to an eaves-drop, in which a friction roller h is placed, for the chain of the crane, with which the stores are raised. The door, when shut, finishes flush with the building, and is therefore of a circular form, framed and double lined, the whole being put together with white-lead paint: each leaf measures 5 inches in thickness at the hinge side, and diminishes to 2½ inches at the meeting edges, as will be understood by examining the section in Fig 3. When the leaves of the door are thrown open, they are kept in their places by catch-hooks of brass, to prevent gusts of wind from shutting them suddenly; f shews a moveable handle or piece of brass rail, within the passage, for laying hold of in stepping off the brazen ladder to enter the house; g shews the upper extremity or highest step of the ladder, which terminates at the sill of the door.

Fig. 2. shews the relative position of the outer and inner entrance-doors, in which a a a is an end view of the former; b b b b a front view of one of the leaves of the inner brass door; e e the outer door check, faced with plates of brass; f the moveable handle or rail, for the greater conveniency of entering the threshold; g the termination and upper step of the brazen-ladder, attached to the building, for communicating with the Rock. h, section of the cornice and friction-roller. The passage being only 2 feet 10 inches in breadth, the rails or moveable handles f, on each side, are made to slide into brass sockets i i, sunk into the walls, and, like the inner door, are flush with the wall when not at use. k k the sockets for the centre-pin hinge of the inner-door.

Fig. 3. is a cross section of one of the leaves of the entrance-door, shewing the position of the brass-case of the hinge-bat, as it lies in the building. A A part of the walls, B B part of the side-walls of passage, C C part of the surface of the outward wall. a a a a is the brass-case, containing the Lewis-bat-tails or palm of the hinge, (described in [Plate XI.] Fig. 3.); b b b b the working-tails; c c the outside lining; d d the inside lining; e e e the frame-work of the door, with the bolts and nails connecting the hinges; f the joint of the hinge, shewing the journal pin-hole; g the half-check joint of the door.

Fig. 4. represents a front view of the door-hinges, lettered in reference to Fig. 3. a a a a is the brass box or case, which is built into the wall for containing the palm-end of the Lewis-hinge; b b is the exterior or working tail, with its screw bolt and nail holes; f f f the double-joint and slip-pin.

Fig. 5. is a cross section of the Lewis-box on the line A B of Fig. 4. with its dove-tail feathers; a a a a shew the parts of the Lewis-bat b c d, as it lies in the box, which is built into the wall.

Fig. 6. represents a longitudinal section of the box and palm of the hinge, shewing its position, in reference to the cross section in Fig. 5. a a a a is the brass box; b and d are the dove-tailed compartments of the palm; c is the tongue or locking-piece; e the pin hole, perforated in the locking-piece, for drawing the parts of the palm in the event of the joint wearing and requiring to be renewed; f f is the slip pin-hole in the other two parts of the palm of the Lewis. The weight of one of the entire hinges of the door, with its Lewis-tail and brass-box was 56 lb., and consequently the four sets for the door weighed about 2 cwt.

Fig. 7. shews the elevation of one of the windows of the Light-house, with part of the exterior wall marked A A A A; one-half of one of the storm-shutters, marked a a, is closed, and the other marked c c, is open; b is a bar of brass, which folds across the window when the shutters are closed, and is used as a stretcher, for preserving them in their places when opened. It will be observed by comparing the close shutter a a with the open one c c, that they are double or cross boarded; they are also fastened with hammered copper nails; d is the clasp used as a handle, which also locks the shutter; e e e e the ends of the dove-tailed hinges as they appear projecting through the walls; f f f f the working-tails of the hinge, forming at the same time the guard-plate of the shutters, as described in Fig. 1. Letter g, upon the open shutter, shews one of the brackets connected with the stretching-bar b, for keeping them open, as will be better understood by examining the following Figure.

Fig. 8. is a plan of one of the window-sills, and a section of one of the storm-shutters, with part of the walls A A, shewing the position of the Lewis-bat cases; a and c, the storm-shutters in an open state; b the stretching-bar in its place, when the shutters are open; e e the exterior ends of the Lewis-bats, with their cases é é é é, which are built into the wall, and, together with the other parts of the hinge, weigh about 28 lb., or 1 cwt. for each set, being one-half of the weight of the door-hinges; g g the brackets connected with the stretching-bar; h h the check in the wall for receiving the shutters; i i the stiles or framing of the outer-window, which opens in two leaves; k k k the framing and case of the inner window, which slides up and down in one sash; l l the balance-weight of the inner-window.

Fig. 9. is a perpendicular section of one of the windows, shewing the triple mode of shutting them during stormy weather. A A a section of a part of the walls. a a, the storm-shutter; h h the check in the building for its reception; i i the frame of the outer-window; k k the inner-window; l the case into which the inner-window drops when not in use.

Fig. 10. A A is a section of part of the thunder-rod and outward wall. a a shew part of the zones or bond-belts, noticed in [Plate VII.] Fig. 7., and [Plate XVI.] Fig. 2.; b b the brass-bats let into the wall, for attaching the thunder-rod with the screws c c, which vary from 2 to 3½ feet apart; d d the thunder-rod, made of the best gun-metal, and weighing at the rate of 7 lb. per lineal foot in the range of the sea, or from the Rock to the entrance-door, and from thence to the Light-room, at the rate of about 4 lb. per lineal foot; e is the joint technically termed Half-checking, by which the pieces, of about 7 feet in length, are connected by two screws at each joint, as shewn in the section. This rod, which extends from the Light-room to the Railways, forms an exterior Conductor, while another, which is not seen here, is connected with the chimney, brazen ladder and railways, and completes the interior conducting process.