CARR ROCK BEACON AS DESIGNED
IN THE YEAR 1810
CARR ROCK BEACON AS EXECUTED
IN THE YEAR 1821
“The upper termination of the beacon, in its present form, as shown in [Fig. X-2], does not admit of the application of the tide machine with the bell apparatus. Experiments as applicable to this have, however, been tried with a wind instrument, to be sounded by the pressure of the sea water, but it has not succeeded to the extent that seems necessary for a purpose of this kind. We have, indeed, thought that the application of pressure as a power, communicated by the waters of the ocean, in mechanical operations, might be carried to almost any extent by simply providing a chamber or dock large enough for the reception of a float or vessel, of dimensions equivalent to the force required. This description of machinery is more particularly applicable in situations where the tides have a great rise, as in the Solway Firth, Bristol Channel, and other parts of the British seas; and at St. Malo on the coast of France.
“A beacon of any form, unprovided with a light, must always be considered an imperfect landmark, and therefore various modes have been contemplated for more completely pointing out the position of the Carr Rock. It has been proposed that phosphoric lights should be exhibited from the top of the building. This object, however, would be more certainly accomplished by the erection of leading lights upon the island of May and mainland of Fife. But these, with other plans, which have been under the writer’s consideration, would necessarily be attended with a great additional expense, which, in the present instance, it is not thought advisable to incur.”
CHAPTER XIII.
CRANES.
It appears that Mr. Stevenson was much perplexed as to what sort of cranes he should use in building the Bell Rock Lighthouse. His difficulties were twofold:—
First, In consequence of the dovetailed form of the stones he required a crane that would drop them as nearly as possible on the beds on which they were permanently to rest.
Second, Supposing he devised a guy crane that overcame this difficulty, what was to be done as the building rose in height, and the guys became too nearly perpendicular to admit of such a crane being used?
In his private notes Mr. Stevenson regrets that he could get no advice from anybody he consulted, all of whom recommended him to employ common sheer poles, such as had been used by Smeaton at the Eddystone; and he adds, “I may say, morning, noon, and night, these difficulties have haunted me.” But thrown back on his own resources, and appreciating the difficulty as no one else could so well do, he found, as is often the case, that he was his own best counsellor, and he succeeded in solving the problem that had given him so much concern, by inventing what he called the “moveable beam crane,” and also the “balance crane,” which are shown in [Plate XI]. The former, as modified to suit particular cases, is now in universal use for building purposes, and the latter has been employed in rearing most of our Rock Lighthouses, so that I think professional readers will not object to my giving Mr. Stevenson’s description of these cranes, as designed by him at the beginning of this century. He says:—