seamen.

The harbour has been, since the reign of George I., under the control and jurisdiction of Commissioners, appointed by parliament. For some years past, the average revenue, arising principally from the shipment of coal, has amounted to about 16,000l. per annum. The funds so collected, have been expended in deepening the shoals, removing rocks and other obstructions and building piers at the mouth of the river. These piers, having been originally executed in a superficial manner, soon showed symptoms of decay, and it was found necessary to rebuild the eastern or seaward portion of them.

The late Mr. John Rennie was consulted, and his advice was, that the piers should be prolonged with solid masonry into deeper water. The south pier has, in consequence, been rebuilt in a substantial manner with ashlar masonry, in blocks of stone, varying from 5 to 7 tons in weight, properly backed with a glacis of rubble stone.

The eastern part of the north pier, during the last ten years, has been taken down, under the author's superintendence; a new pier has also been built, in the direction suggested by Mr. Rennie, and approved, by his son Sir John Rennie. This pier has been executed in the strongest manner and with excellent materials, forming altogether a handsome and substantial piece of masonry. The most beneficial effects have been produced by the adoption of these plans; the channel to sea has been straightened and deepened by dredging, and the bar has been lowered and kept in a stationary position, so as to give 4 feet of water upon it during low water, or 18 feet at high water of ordinary spring tides.

Near the termination of the north pier, there was built, in 1802, by Mr. Pickernell, then engineer to the Commissioners, an octagonal lighthouse of polished stone. Its height was 60 feet 2 inches from the base to the cornice, terminating with a lantern, the

cupola of which was 16 feet above the cornice, making a total elevation of 76 feet 2 inches above the pier. Its breadth was 15 feet at the base and 8 feet 6 inches at the cornice, having a spiral staircase up the centre of the building. It was subsequently lighted with coal gas from nine patent burners with parabolic reflectors.

In the beginning of the year 1841, before the works at the north pier-head were terminated, an alarming breach was made by the sea in the projecting part of the old pier, on which this lighthouse stood, and it became imperative, either to take down the building immediately, or to repair the pier in an expensive manner.

On the 7th of April 1841, the advantages of having a new lighthouse on the high ground near the fort on the south side of the river, and the difficulties of removing the present one from its then critical situation, were discussed at the Board of Commissioners. The result was, that the author (Mr. Murray) received directions to prepare the materials necessary for carrying into effect the project he had suggested of removing the building in an entire state, on a cradle of timber, to the eastern extremity of the new pier.

In consequence of the breach before alluded to it was necessary to remove the lighthouse in a northerly direction, on to the new pier, before it could be taken to the eastward, and its axis required to be turned in order to make it correspond, or be parallel with the altered direction east and west of the new pier. The raised platform of the new pierhead, where the building was proposed to be placed, being 1 foot 7 in. higher than the original site of the lighthouse, it became necessary, in providing a proper height for the entrance doorway, either to descend a few steps from the platform or to lift the base, and consequently the whole building, to the proper level. It was deemed advisable

to adopt the latter course.

The first of these operations was to take the building northward. On the 15th June the masons began to cut apertures on the north and south sides of the building for the reception of the cradle or platform of timber, see plan, fig. 2, and elevation, fig. 3, the two middle balks were threaded through consecutively, and the apertures were made no larger than absolutely necessary for that purpose. The upper course of stones below the torus moulding was not disturbed, and the bottom of this course was made to rest immediately upon the cradle timbers. The upper surfaces of the beams, where they

were in contact with the masonry, were covered with thin sheet lead, to equalise the pressure. When the timbers were threaded through the building, screws were applied beneath them, until they were closely pressed to the course of masonry, and uprights of

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timber were then inserted and firmly wedged up, which allowed the screws to be removed. Less difficulty was experienced in inserting the next timbers, which were parallel to the other pair and supported the external masonry; they were covered with lead like the

others, screwed up and shored with timber uprights and wedges in a similar way. Care was taken to place all these shores in such positions, that they should not interfere with the insertion of the lower transverse tier of timbers,

An aperture was next cut on the eastern side of the base (the entrance door on the west side not requiring any), to admit the two transverse beams, which were firmly screwed up underneath the beams previously inserted, and then shored with uprights and

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Other tim

wedges to relieve the screws. bers were next inserted aud shored up in pairs, in a similar way to the others, and when all these were secured other apertures were cut through the building to admit the upper timbers.

The next operation was the insertion of the timbers, with the rails fixed upon them. The centre timbers immediately below the upper beams were fixed first. These were firmly bedded on the stone pavement of the pier, and upon the solid masonry of the new work. The sheave balks to each were then threaded through the building, and firmly wedged to the timbers above, and to the rails below, by a series of wedges. The other rail and sheave balks were placed in a similar manner underneath each upper timber, and in the order in which they were inserted in the building. Finally, when all these wheels were brought to their bearing, the small portions of the original masonry left in the four corners of the building were cut away at one time, and the two remaining intermediate upper timbers were threaded through and secured.

While these works were in operation, the octagonal shaft was tied together in the following manner. Two planks, 44 feet in length, and 3 inches in thickness, were suspended from the cornice at each angle of the shaft, and then lashed closely to the masonry by ropes and wedges. Five horizontal tiers of iron straps, 2 inches broad, and seveneighths inch thick, were made to embrace the building, and these were drawn closely up by screws to the above-mentioned planks and filling-in pieces.

Immediately above the cornice, and on a level with the light-room floor, eight apertures were made through the walls (which were here only 10 inches in thickness), and pieces of timber were pushed through the apertures from the inside, and drawn back again till they met in the centre. Strong plates of malleable iron covered the joints above and below the timbers, and screwed bolts passed through the whole. This upper platform was connected with the cradle below by a large chain passing round a strong bar of iron at the top of the platform, and round a similar bar of iron on the lower side of the cradle, and the chain was drawn tight by a large screw.

The upper platform was further connected externally with the cradle by eight main uprights of timber 12 inches square, tenoned into the horizontal timbers at the cornice, and brought close to the masonry of the building at the base, and secured to the cradle and upper platform by stirrup-straps and bolts. The uprights were united together by three tiers of chock-pieces. Three

iron straps, 34 inches broad, and 1 inch thick, passed round the chock pieces and uprights, and the whole was drawn closely to the building by screws.

The raking braces were next erected, and their feet passed between the timbers of the cradle and cill-beams fixed thereon, so that the whole framing could be firmly bound together (fig. 3). The four diagonal beams and ledges fixed to the raking braces, further prevented any of the timbers from springing or twisting.

Up each angle of the building, above the cornice, battens, 2 inches thick, were fixed, with two tiers of horizontal junction pieces, kept together by binding screw straps. The dome of the building, which is of iron, covered with lead, was fastened by chains passing round the summit and the upper cornice, and continued down to the projecting timber of the upper platform, each chain being tightened by screws. The large plates of glass of the light-room were taken out, and window sashes, with ordinary crown glass, were put in their place. The light, however, was exhibited nightly, as usual, during all the operations of removal; a lead pipe, lengthened as required, being connected with the gas-works on the pier.

On the 2nd of August everything was prepared for drawing the building northward. For this purpose, five pulling screws were strongly fixed to the glacis of the pier, north of the building, and chains were attached to them, and to the cradle upon which the lighthouse rested. These screws were worked by twenty-four men. Four forcing screws, worked by three men to each, were applied behind the cradle, to assist in propelling it. The total number of men employed on the occasion was forty. The cradle was supported on one hundred and forty-four wheels, which travelled on eight parallel lines of rails, but the extreme ends of the cradle were supported and moved on slide balks only. The operations for the removal northward were commenced at half-past 3 P. M., and at a few minutes after 8 P. M. it was safely landed on the new pier. The distance travelled was 20 feet 5 inches.

On the 7th of August the building was drawn, in a similar manner, to a further distance northward of 8 feet 1 inch.

The cradle was then shored with timber uprights, which allowed the railway and sheave balks to be withdrawn and reversed, for the purpose of taking the building to the eastward.

It is unnecessary to describe the process of placing these railway and sheave balks in a direction bearing east and west, as it is merely a repetition of the same operations