Smeaton and Lighthouses / A Popular Biography, with an Historical Introduction and Sequel

by Anonymous

Up to this point all the courses had been begun by the stones that were securely dove-tailed into the rock, and further made fast by oak-wedges and cement. To receive these wedges, two grooves were cut in the waist of each stone, from the top to the bottom of the course, of an inch in depth and three inches in width. The care with which the foundation-work was carried on may be gathered from Smeaton’s description of the manner of laying each stone. ‘The stone to be set being hung in the tackle, and its bed of mortar spread, was then lowered into its place, and beat with a heavy wooden maul, and levelled with a spirit level; and the stone being accurately brought to its marks, it was then considered as set in its place. The business now was to retain it exactly in that position, notwithstanding the utmost violence of the sea might come upon it, before the mortar was hard enough to resist it. The carpenter now dropped into each groove two of the oaken wedges, one upon its head, the other with its point downwards, so that the two wedges in each groove would lie heads and points. With a bar of iron about two inches and a half broad, a quarter of an inch thick, and two feet and a half long, the ends being square, he could easily (as with a rammer) drive down one wedge upon the other; very gently at first, so that the opposite pairs of wedges being equally tightened, they would equally resist each other, and the stone would therefore keep place. A couple of wedges were also, in like manner, pitched at the top of each groove; the dormant wedge, or that with the point upward, being held in the hand, while the drift-wedge, or that with its point downward, was driven with a hammer. The whole of what remained above the upper surface of the stone was then cut off with a saw or chisel: and generally, a couple of thin wedges were driven very moderately at the butt-end of the stone; whose tendency being to force it out of its dove-tail, they would, by moderate driving, only tend to preserve the whole mass steady together, in opposition to the violent agitation that might arise from the sea.’ In addition to this, a couple of holes having been bored through every piece of stone, one course was bound to another by oak trenails driven stiffly through, and made so fast that they could more easily be torn asunder than pulled out again. ‘No assignable power,’ says Smeaton, ‘less than what would by main stress pull these trenails in two could lift one of these stones from their beds when so fixed, exclusive of their natural weight, as all agitation was prevented by the lateral wedges.’ The stone being thus fixed, a proper quantity of mortar was liquefied; and the joints having been carefully pointed, up to the upper surface, this mortar or cement was poured in with iron ladles so as to occupy every void space. The more consistent parts of this cement naturally settled to the bottom, and the watery parts were absorbed by the stone: the vacancy thus left at the top was repeatedly refilled, until all remained solid; the top was then pointed, and, when necessary, defended by a coat of plaster. When the whole of the foundation was in this manner brought to a level, some other means was necessary of attaining the like degree of security. For this purpose the central stone of the sixth course had a hole of one foot square cut quite through the middle. Eight other depressions of one foot square and six inches deep were also sunk at equal distances in the circumference. A plug of strong hard marble, from the rocks near Plymouth, one foot square and twenty-two inches in length, was set with mortar in the central cavity, and fixed firmly therein with their wedges. This course was thirteen inches in height, so that the marble plug, which reached through it, stood nine inches above the surface. Upon this the centre-stone of the seventh course was fixed, having a similar hole made in its centre, bedded with mortar and wedged as before. By this means no force of the sea acting horizontally upon the centre-stone, less than what was capable of cutting the marble plug in two, was able to move it from its place; and to prevent the stone the more effectually from being lifted, in case its bed of mortar should happen to be destroyed, it was fixed down by four trenails. The stones surrounding the central stone were dove-tailed to it in the same manner as before, and thus the courses proceeded with no other interruption than arose from the nature of the situation.

Smeaton tells us that when the work had proceeded so far as to afford a level platform, the pleasure he took in it, and the novelty of the thing, led him to walk to and fro upon it with much complacency. But making a false step, and not being able to recover himself, he tumbled over the brink of the work down among the rocks on the west side. The tide had then retreated, so that no serious result happened, but in his fall he dislocated his thumb, and as no medical aid could be procured, he set it himself, and then returned to his work. It was more than six months, however, before he recovered the full use of his thumb.

Owing to very boisterous weather, and repeated losses of the necessary materials left on the rock, the seventh course was not laid until the 7th of September. But Smeaton had the satisfaction to find that all the work actually completed, stood the utmost severity of the weather unmoved. At this time the sea became so calm that the work proceeded rapidly, and for three days in succession the top of the work was not wetted. The eighth course was completed on the 13th, but the weather again becoming unfavourable, the ninth was not finished until the 30th, and here Smeaton found it desirable to close the operations for this year.

The ensuing winter was of so stormy a nature as severely to test the strength of the work at the Eddystone. Smeaton went early in the spring to view it, and says, ‘I was much surprised, notwithstanding what had been reported of the soundness of the work, to find it so perfectly entire, for, except a small spawl which had been washed from the rock itself, the whole did not seem to have suffered a diminution of so much as a grain of sand since I left it on the 1st of October: on the contrary, the cement, and even the grouted part, appeared to be as hard as the stone itself, the whole having become one solid mass, and, indeed, it had quite that appearance, as it was covered with the same coat of sea-weed as the rock, the top of the work excepted, which was washed clean and white.’

Various disasters to the vessels, moorings, &c. near the rock retarded the work in the spring of 1758. It was not till the 10th of July that the eleventh course was finished. Twelve days afterwards the twelfth course was laid down. After this the work went on better, so that on the 8th of August the fourteenth course was completed, and with it what was called the fundamental solid. From hence begins the building also called the Solid, which includes the passage from the entry-door to the well-hole for the stairs. It was now necessary for the sake of the well-hole to omit the centre-stone. The four stones surrounding the centre were therefore fastened together by what are called hook-scarf joints, so as to compose, in effect, one stone. Means were also taken to prevent them from shifting, or being lifted out of their position.

From the 9th to the 20th of August there was an uninterrupted continuance of fine weather, so that great progress was made. By the latter day the eighteenth course was completed, which reunited the building into a complete circle, by covering the passage to the staircase. Over the head of the entry-door the figures 1758 were cut in deep characters. During another month, by great exertions, the twenty-fourth course was reached and completed. This course finished the Solid, and formed the floor of the store-room, so that Smeaton had every reason to be satisfied with the work of this season; yet as he had been long meditating on the advantage to the public which would accrue from setting up a light during that very winter, he resolved to make a vigorous effort to get the store-room completed and a light erected above it.

The building had hitherto been carried up solid as high as there was any reason to suppose it exposed to the heavy stroke of the sea, i. e. to thirty-five feet four inches above its base, and twenty-seven feet above the top of the rock, on the common spring-tide high-water mark. At this height it was reduced to sixteen feet eight inches diameter; and it was necessary to make the best use of this space, and make all the room and convenience therein that was possible, consistent with the still necessary strength. The rooms being made twelve feet four inches in diameter would leave twenty-six inches for the thickness of the walls. These walls were made of single blocks in the thickness, so shaped that sixteen pieces formed a complete circle, and from their figure composed a stout wall. These pieces were cramped together with iron, and also secured to the lower courses by marble plugs as before. To hinder the passage of wet through the upright joints, flat stones were introduced into each joint so as partly to be lodged in one stone, partly in another, thus making it tolerably certain that the rooms would be kept comfortable and dry in all weathers. On the 30th of September the twenty-eighth course was completely set. This and the next course received the vaulted floor, which made the ceiling of the store-room and floor of the upper store-room. For further security, therefore, there was a groove cut round the upper surface of this course, in which was placed a circular chain of great strength. Upon this chain, in the groove, was poured melted lead, until the cavity was filled up. The next course was then laid on, and this was also secured by a chain in like manner, it being considered that the courses on which the floors rested demanded every possible security. The formation of the floors, and the care taken to avoid the danger of lateral pressure on the walls, is worthy of notice. Each floor rested upon two courses; being firmly supported by a triple ledge going circularly round the two supporting courses. ‘Had each floor,’ says the architect, ‘been composed of a single stone, this lying upon the horizontal bearings furnished by these ledges, would, while it remained entire, have no lateral pressure or tendency to thrust out the sides of the encompassing walls; and that in effect the several pieces of which the floors were really composed might have the same property as whole stones, the centre stone was made large enough to admit of an opening, from floor to floor, to be made through it; and being furnished with dove-tails on its four sides, like those of the entire solid, it became the means by which all the stones in each floor were connected together; and consequently, the whole would lie upon the ledges like a single stone, without any tendency to spread the walls. But if by the accident of a heavy body falling, or otherwise, any of those stones should be broken, though this might not destroy its use as a floor; yet the parts would then exert their lateral pressure against the walls; and, therefore, as a security against this, it became necessary that the circle of the enclosing walls should be bound together, and the building, as it were, hooped.’ Thus assiduously did Smeaton urge forward the work, yet without neglecting any of the necessary precautions for its safety. By the 10th of October he had nearly completed all the necessary arrangements for establishing a light and light-keepers at the Eddystone during the same winter, when he received an unexpected and painful refusal from the Corporation of Trinity-House, to the effect that ‘on reading the Acts of Parliament, the application from the merchants and owners of ships, and Winstanley’s narrative of the first lighthouse erected there, they are of opinion that a light cannot be exhibited on the Eddystone Rock till the lighthouse is re-built.’

Smeaton employed the winter of 1758-9 in London, preparing everything for the final work at the Eddystone the ensuing season. He formed and made out designs for the iron rails of the balcony, the cast iron, the wrought iron, and the copper-works of the lantern, &c. There was a violent storm on the 9th of March, 1759, which it was supposed might have damaged the unfinished lighthouse, as it had done very great damage to the ships and houses at Plymouth. As soon as it was possible to effect a landing the works were visited and a report sent to Smeaton. From this he found, with pleasure, that not only the solid but the hollow work remained perfectly sound and firm; all the mortar having become quite hard, and every part of the work just as it was left by the workmen in October.

The commencement of the work for the next and last season, took place on the 5th of July. On the 21st of the same month the second floor was finished, and by the 29th the fortieth course of stone was laid down, and the third floor finished.

The main column of the lighthouse was completed on Friday, August 17th. It contained in all forty-six courses of stone, and reached the height of seventy feet. The beds for the light-keepers were fixed in the uppermost room, and the kitchen with its fire-place in the room below it, whereas in the former house, the kitchen had been the upper room, doubtless, because the funnel for the smoke would be shorter. But Smeaton having been informed that with the former arrangement the beds and bedding were in a very damp and disagreeable state, proposed to remedy the evil by allowing the copper funnel to pass through the bed-room, and thus to dry the air. This plan completely answered the desired end; though it must be observed, that the whole edifice, even those portions of it which were continually subject to the action of the waves, were much more impervious to moisture than Rudyerd’s edifice; as may naturally be imagined from the difference of material used in the building of the lighthouse, and the well-known quality of granite to resist humidity. In the upper room, therefore, were fixed three cabin-beds to hold one man each, with three drawers and two lockers in each to hold his separate property. In the kitchen, besides the fire-place and sink, were two settles with lockers, a dresser with drawers, two cupboards and one platter-case. In the lantern a seat was fixed to encompass it all round, except at the doorway, and this served equally to sit upon, or to stand and snuff the candles; also to enable a person to look through the lowest tier of glass-panes at distant objects, without having occasion to go on the outside of the lantern into the balcony.