As to the construction of the Light-house itself, we are of opinion, that it is much better to follow what has been found to answer at the Edystone, a situation nearly similar to the present, than, in a work so important, to look for other methods that have not stood the test of trial. It must, however, be observed, that some alteration, suited to the difference of local circumstances, ought to be adopted. The Rock at the Edystone differs both in form and quality from the Bell Rock; it lies in a slanting direction, and the higher part was never covered by the tide. It is of a harder quality, and but small in size; nothing, therefore, was to be found in this case in regard to the wearing or wasting of the Rock; and from its limited size, there was no more space than what merely enabled the engineer to make the erection upon it.
The case at the Bell Rock is very different, the Rock being, on an average, not more than four feet higher than low-water of spring-tides. It is of a softer quality, but the dimensions are large. It therefore becomes necessary that the base should be more extended and flat where it is connected with the Rock, so that when the waves break upon it, they may spend their fury on the base of the Light-house, instead of the Rock itself, and thereby prevent it from wearing away. The tower should also be higher, as the tide rises more upon it than on the Edystone. These, and a few other alterations, will adapt the Edystone plan to the Bell Rock, unless in so far as the light itself is connected; but this need not now be a subject of inquiry. A Plan of the Light-house, nearly similar to what is proposed, is handed herewith, but no plan of the dove-tailing has been made, nor can it well be done at present, as the dove-tails must be suited to the different courses of stone as they come from the quarry; but, as the principle is similar to that of the Edystone, the design may be easily judged of.
It is of much importance, that, in so hazardous a work as the present, recourse should speedily be had to advice when occasion requires; and, as a Quorum at all times cannot be got, it might be advisable to appoint a Sub-Committee of your number, to be called together when necessity may require.
(Signed) John Rennie.
Robert Stevenson.
To the Honourable the Commissioners of the Northern Light-houses.
REPORT by Mr Rennie.
Edinburgh, October 29. 1807.
Gentlemen,
I went to the Bell Rock on the 5th instant, when I found Mr Stevenson with his workmen engaged in preparing the Rock to receive the foundation of the Light-house; also in erecting a Beacon on it, for the double purpose of pointing out to mariners the situation of the Rock more correctly than can be done by the Floating-Light, and as an asylum to the men employed on the Rock, in case they should be overtaken by the tide before the boats had time to take them to the vessel. Mr Stevenson had been constantly engaged in the different operations for about two months, during which time he had never been ashore; and it was fortunate he had taken the resolution of remaining constantly on board, for, without this, there is every reason to believe that the workmen could not have been prevailed on to continue at the work, they having previously shewn a disposition to leave it; but by perseverance, and by allowing them their provisions while on board the vessel and working at the Rock, they have not only been prevailed on to remain at the work, but they now seem to be better satisfied when at the Rock than on shore; and as no accident has happened, although the weather has several times been very stormy, there is great reason to believe that the workmen, being now accustomed to the work, and having gained entire confidence by the success of the past year, will return with redoubled vigour next season, and that the work will proceed with much spirit and regularity.