Fig. 5.
The Bell Rock was the first lighthouse that was illuminated by Mr. Stevenson’s improved apparatus (shown in section in [Fig. 4]), where a is the fountain for the oil, b the burner, and the directions of the incident and reflected rays are represented by dotted lines. In [Fig. 5] the reflector is shown in elevation; the lamp is represented as lowered down from the reflector, which is effected by a sliding arrangement controlled by a guide,—the object being to allow the lamp to be removed while the reflector is being polished, and to insure its being returned to its exact position in the true focus of the reflector. Perhaps the most valuable opinion that can be quoted as to the utility of this arrangement is that of Mr. Airy, the Astronomer-Royal, who, after the apparatus had been in use fifty years, and after having inspected the lighthouses both of Britain and France, says—“This lighthouse” (Girdleness, in Aberdeenshire) “contains two systems of lights. The lower, at about two-fifths of the height of the building, consists of thirteen parabolic reflectors of the usual form. I remarked in these, that by a simple construction, which I have not seen elsewhere, great facility is given for the withdrawal and safe return of the lamps, for adjusting the lamps, and for cleaning the mirrors;” and in closing his report he adds, “It is the best lighthouse that I have seen.”[6]
Notwithstanding the introduction of this improved apparatus at the Bell Rock in 1811, a coal-fire, which had existed for the long period of 181 years on the Isle of May, at the entrance to the Firth of Forth, still continued, in 1816, to send forth its feeble and misleading light, and as it was one of the best specimens of the lighthouses of days now passed away, it may not be uninteresting to give a short account of it.
The May light was at that period what is called a “private light”—the right of levying dues on shipping being vested in the Duke of Portland, who was owner of the island. There were many private lights in England, but the Isle of May was the only one that still remained in Scotland, and the Commissioners of Northern Lighthouses, believing it to be advantageous that so important a light should be placed under public management, so as to secure for the shipping a better light, and exemption from the high passing tolls charged by the proprietor, entered into treaty with the Duke of Portland for the purchase of his rights. This negotiation resulted in the introduction of a Bill into Parliament in 1814, authorising the purchase of the Isle of May, with the right of levying toll, for the sum of £60,000.
So soon as the property came into the hands of the Commissioners they erected a new lighthouse, and on the 1st of February 1816 the old coal chauffer was discontinued, and a light from oil with reflectors was exhibited in its stead. I am enabled from an old plan in my possession to present the reader with two sketches of the original chauffer light of the Isle of May.
Fig. 6.
[Fig. 6] is an elevation of the building, with the tackle for raising the fuel to the top, and its inscription stone over the door bearing the date 1635. [Fig. 7] shows the building in section, with its stone winding staircase and vaulted chambers, the whole structure apparently being so designed as to be perfectly proof against fire—a precaution very necessary for a building dedicated to such a purpose, for it is recorded that no fewer than 400 tons of coal were annually consumed in the open chauffer on its top.
Fig. 7.