While, however, this tribute is justly due, and ought to be paid, to the memory of Mr. Rennie, Mr. Logan, under whose care the work was more immediately executed, ought not to be forgotten. Perhaps no man was ever more capable of executing stone-work to bear the violence of the sea ; and, let the plan be ever so good, a work may be rendered unstable by ignorant or negligent execution. Logan had been trained from his infancy in aquatic architecture, more especially in the construction of bridges which had to resist the action of violent floods ; and, therefore, though a very young man when employed in the Bell-rock Lighthouse, he well knew the nature of the work, and was most faithful in the execu tion of it. His execution of the Dundee harbour, under Telfird, and of the packet harbours between Ireland and Scotland, under Rennie, are lasting monuments of his ability ; and had he not been prematurely cut off there is no doubt that his operations on the Clyde would have been of the greatest benefit to Glasgow, and to all who are any way connected with it. Indeed, his professional zeal may he considered as the real cause which shortened his days ; for when laying the foundations of the Dundee harbour, some of which was in very deep water, he was constantly on the ground when the tide permitted, and standing in the water for hours, directing and encouraging the men, whether it was night or day, and whatever was the state of the weather. This labour and exposure, which would very soon have killed most men, brought upon him a severe and long-protracted rheumatic fever ; and, though the natural strength of his constitution enabled him to survive this for many years, he neve; thoroughly recovered from it.
In enumerating those who were chiefly instrumental in making the Bell-rock Lighthouse what it is, there is another and a different character, whom it would be injustice to pass over in silence : this was Watt, the machinist, or, more strictly speaking, the man of all work, or rather of all contrivance in cases of emergency. As is but too frequently the case with workmen of great inventive talent, Watt was somewhat dissipated, and passed not a little of his time in ale-houses. In this matter he was allowed to have his way, only to he always ready at a call ; and when the course of the work rendered a crane, or crab, or other engine of peculiar con struction, necessary, Watt was sent for, and instantly sketched out, rudely enough in some instances, the very machine which answered the purpose ; and having done so, he returned to his potations. Among his contrivances we may mention two cranes, which are certainly superior to any other for laying heavy stone in difficult situations. One of those was a " jib-crane," of great power and easy management : it was supported by four gye-ropes in the usual manner, and traversed freely all round. The jib or arm was jointed to the pillar, so that it could be brought into all positions from hori zontal to vertical ; and, to prevent it from lapping to the pillar when raised, or beyond a certain elevation, the jib-chain by which it was raised or lowered passed over a pally in the bight, so as always to give a downward pressure on the point of the jib, where the pully of the crane chain was attached.
It was worked by wheel and pinion. and, of course, required two sets of " geer "—one for working the jib, and the other for working the crane. By means of these contrivances, the largest stones—some of which were two tons in weight—could be brought to any point within the range of the jib, with great certainty, and very little manual labour.
While the building was solid, and of such moderate height as that the gye-ropes could be fastened, this crane answered exceedingly well ; but after the structure had advanced some height, and especially after it began to be hollow, a crane of this description could not be so fastened as to command the whole surface and have sufficient security. Consequently, the invention of Watt had to be called in ; and he contrived his counterpoise crane. This crane was supported on a hollow pillar of cast-iron, which was lengthened by adding additional pieces as the progress of the work required. The crane, which was a platform with two equal arms, traversed upon this pillar, and was of sufficient length to command the whole work, and as much more as sufficed for raising the stones. To the one arm was attached the chain for this pur pose, while the other carried a hook, upon which weights could be placed, to counterbalance that of the stone ; and the work ing parts were so arranged, that when the stone required to be moved outwards or inwards to bring it to its proper lied, the weights were also moved outwards or inwards, and thus the leverage of both ends of the crane was always equal, as well as the weight. Thus it traversed freely, was easily worked, and perfectly stable. One of the barrels also raised the plat form of the crane by means of a pulley and chain on the top of the pillar ; and there were apertures through both sides of the pillar, for supporting the platform when raised to the proper height. When the pillar itself required to be lengthened, the pulley was removed from the top of the pillar, a new piece of pillar added, the pulley replaced, and the chain lengthened and passed over it as before. In this way, by adding length after length, the laying of the stones by means of the counterpoise crane was carried on to the required height with ease, expedition, and safety, which could not have been maintained without such an apparatus.
The lighthouse itself is a splendid structure, of which the external contour is good, and also the execution. The height of the masonry is 100 feet, and the light-room or lantern is 15 feet more. The diameter at the base is 42 feet ; but at the parapet of the lantern, is only 13 feet. The first 30 feet consist of solid masonry, the lower courses let in, and treenailed to the rock, and all the solid courses are dovetailed, joggled, and treenailed; and as they are laid in strong mortar, which sets readily and firmly, the whole of this 30 feet has very nearly the cohesion of one solid mass of stone.