In a highly interesting lecture which the writer of the Notes delivered at Arbroath, about a year ago, he thus described the lightroom and lighting apparatus, which had just been renewed, not on account of tear and wear, but to bring it up to present day standard:—
“In the centre of the floor stands the revolving machinery enclosed in a heavy metal case, upon which the huge lens, with its supporting carriage, revolves. The lens itself—a marvel of the glassmaker’s art—is the production of a French firm. Imagine a huge saucer, twelve feet in diameter, composed of twenty concentric prisms of purest glass, each with a diameter almost as much as a man may enclose with both hands, terminating centrally in a sixteen inch plano-convex lens or bull’s-eye. Suppose the rim of this saucer to the extent of four prisms be turned sharply inwards, the whole set vertically on edge—convexity outwards—and a vertical section—in which the bull’s-eye and three adjoining prisms are alone intact—projected a foot further forward, one may gain some idea of that particular portion of the lens allotted to the red flash, the colour of which is attained by means of sheets of red glass attached inside the central section and on the outside of the adjoining wings. On the opposite side of the lens, and in a line with the central red section, is a similar section—minus the adjoining wings and the red media—through which the white flash is transmitted. Both flashes are intended to equal each other in intensity, which accounts for the much smaller portion of the lens allotted to the white. A belt of horizontal prisms, three feet wide, connects the wings of the red section with the white on either side, and reflects the rays of light equally to both sections. Stooping underneath this belt, access is obtained to a fixed circular platform in the interior of the lens. In the centre of this platform, upon an iron pedestal, is placed the source of illumination, a large six-wick lamp. Between this platform and the top of the machine case, the circular carriage upon which the superstructure of the lens is erected revolves upon twelve five-inch steel rollers travelling upon a circular metal pathway. Attached to the under side of this carriage is a heavy gun-metal ring, six feet in diameter, toothed on its inner circumference, which engages with a horizontal pinion wheel rising from the corner of the machine case, and through which the driving power is transmitted. The machine—an exaggerated form of clockwork—is driven by a weight of 400 lbs. travelling in the centre of the spiral stair on the first flat. The speed of the machine is regulated by adjustable fans; and a speed indicator, furnished with an alarm bell, intimates the periods of winding—an operation necessitating two minutes’ stiff winding every half-hour. The entire lens, with its supporting carriage, is estimated to weigh about six tons. The lamp, as I have already stated, is placed upon an iron pedestal in the centre of the platform, or service table, as it is called, in the interior of the lens. It is fitted with what is known as the stepped Doty burner, and carries six concentric wicks, each slightly elevated above the other towards the centre. The burner is six inches in diameter, and consumes paraffin oil at the rate of eighteen gills per hour. To maintain this supply, a forty gallon tank of polished brass is placed on the lightroom floor; and a small force pump, with triple plungers, working in conjunction with the revolving machine, maintains a constant supply of oil, which is kept cool by circulating within an inch of the burning edge of the wicks, the surplus oil returning to the pump-tank. The flash, on being transmitted through the lens, is reckoned to be equal to 60,000 candles; and the characteristic of the light—a red and white flash alternately every half-minute—visible twenty miles distant.”
A description of the work of renewal of the lighting apparatus and the erection of a new and enlarged lantern to hold it on the top of the tower, is also given in the Notes; and no further reference to it is needed than to say that the light, which has the same characteristic as before, is now, by means of the new apparatus, made much stronger and more brilliant.
Such an erection as this lighthouse—standing, as it were, a pillar in the ocean, with a stormy sea raging round it—may surely be described as one of the noblest and most wonderful works of man. As no ship has been wrecked on the Rock since the light was first exhibited, it is incalculable how many valuable lives may have been saved by it. Sir Walter Scott, on the occasion of his visiting the Bell Rock as the guest of the Commissioners on their annual tour of inspection in 1814, gave beautiful expression to his feelings in the following appropriate lines, which he wrote in the Lighthouse Album:—
Pharos Loquitur.
Far in the bosom of the deep,
O’er these wild shelves my watch I keep,
A ruddy gem of changeful light
Bound on the dusky brow of night;
The seaman bids my lustre hail