38 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



f February, 



in that year, the author and his son laid the foundation of Maplin 

 Sand Lighthouse. (See Jnuriml, Vol. V., 1842, p. 352.) 



Before determininfr the leii^tli of the piles and the area of the 

 screws to be employed, a careful examination of the frround was 

 made, and it was ])roii<)scd to use nine malleable iron piles of S in. 

 diameter, and 26 feet in length, with a cast-iron screw of i feet 

 diameter, secured to the foot of each. Eight of the piles were 

 placed at the angles of an octagon, and one in the centre; these 

 were put down in nine consecutive days, being screwed into the 

 bank to the depth of 22 feet, leaving 4 feet above the surface. 

 The tide rises on the bank about 16 feet, and seldom leaves the 

 surface dry. The instrument used in trying the nature of the 

 ground was also employed in testing its holding power. It con- 

 sisted of a jointed rod 30 feet long, and 1^ inch diameter, having 

 at its foot a spiial flange of 6 inches diameter. It was moved 

 round by means of cross levers, keyed upon the boring-rod : and 

 upon those levers, when the screw was turned to the depth of 27 

 feet, a few boards were laid, forming a platform sufficiently large to 

 support twelve men. A bar was then driven into the bank at some 

 distance, its top being brought to the same level as that of the 

 boring-rod. Twelve men were then placed upon the platform to 

 ascertain if their weight, together with the apparatus, in all about 

 one ton, sufficed to depress the screw. After some time, the men 

 were removed, and the level was again applied : but no sensible 

 depression of the screw could be observed. 



Although this was the first screw-pile foundation that was laid 

 for the reception of a lighthouse on a bank of loose sand covered 

 by the sea, it was not the first that was erected, as the piles re- 

 mained untouched for two years, in order to ascertain if any change 

 would occur from the action of the sea, or other causes. 



Pending this term of probation, a lighthouse was proposed to he 

 erected in Morecombe Bay, and it was decided to use screw-piles 

 for the foundation. The novelty of the work, the peculiarity of 

 the situation, and the dread of failure if it were intrusted to stran- 

 gers or those who were not interested in it, rendered it obligatory 

 upon the author and his son not only to send in a design for the 

 foundation, but also for the superstructure, and afterwards to 

 devote their attention most assiduously to the superintendence of 

 the erection of the whole structure, which was commenced in the 

 latter part of 1839, and the lantern was lighted on the 6th of June, 

 1840, — every part, with the exception of the top of the lantern, 

 being completed in the month of March. As this lighthouse was 

 the first of its kind, aiul it was, perhaps, the first attempt to place 

 a habitation of any description in a position so proverbially un- 

 stable, a short description of the structure and of the locality be- 

 comes necessary. 



The situation selected for the lighthouse (see Journal, Vol. III., 

 1840, p. 181) is about two miles from the nearest shore, on the 

 verge of a bank of loose sand, which shifted occasionally, until it 

 was fixed beneath and around the house by a superposed mass, 

 several feet deep, of strong argillaceous earth and stones. It may 

 be remarked, that banks of pure sand are very liable to shift at 

 their surface, and it is extremely difficult to penetrate them to any 

 considerable depth, the absence of clay or any plastic material ren- 

 dering the particles nearly incompressible. In this case, seven 

 wrought-iron piles, 16 feet long, with cast-iron screws 3 feet in 

 diameter, were employed, one being placed at each angle of a 

 hexagon, and one in the centre. Seven balks of Baltic timber, 

 14 inches square, of the best quality, were selected for the sup- 

 ports of the house ; the six exterior balks were each 48 feet long, 

 and the centre one was 57 feet in length, to admit of its rising 

 through the house to the base of the lantern, which it assists in 

 supporting, and to give additional stability to the whole structure. 

 In the foot of each of these supports, a hole, 5 inches in diameter, 

 was bored to the depth of 7 feet, to receive the end of the pile 

 upon which it was shipped ; and to strengthen them for the same 

 distance upwards, several strong iron hoops were driven on hot. A 

 small spiral flange was fixed on the foot of each balk, to draw it 

 into the sand, in the same manner as in putting down the piles. 

 The diameter of the hexagonal base is 50 feet, and the diameter of 

 the platform on which the house stands is 27 feet ; the exterior 

 piles having an inclination inwards of 1 foot in 5. It should be ob- 

 served, that any degree of inclination can be given to a pile whilst 

 it is in motion, by merely placing at a corresponding angle the 

 platform upon which the men work. The floor of the house is 45 

 feet above the surface of the bank, and the tide rises about 32 feet 

 on the supports, at the equinoctial springs. 



A more detailed account of this lighthouse would be superfluous, 

 the remainder of the work being of the ordin.iry character for 

 structures of this kind; l)ut it may he observed that since the time 

 of its erection in the winter of 1839 and '40, the only repair it has 



received or required is the occasional application of a little paint. 

 The total expense of this house was about 3,350/., of which the 

 dioptric apparatus for lighting cost nearly 1,000/. 



This, as before observed, being the first lighthouse placed on a 

 bank of loose sand covered by the sea, and from its proximity to a 

 deep channel, entering fairly into competition with floating lights, 

 a few words on the comparative merits of fixed and floating lights 

 may not be out of place. 



In looking out at night for narrow and intricate channels far 

 from land, it is of the utmost importance that tlie mariner should 

 rely with undoubting confidence, not only on the stability of the 

 light, but also on its unvarying position and appearance. All these 

 advantages are possessed by the Fleetwood lighthouse, and the 

 others constructed on the same principle ; but in tempestous wea- 

 ther, the floating light ships are nearly obscured by the spray, and 

 their lights have no steadiness, on account of the constant motion, 

 whilst hundreds of lives and millions of property have been lost in 

 consequence of their breaking from their moorings. Nor can they 

 be said to occupy any precise position, shifting as they do with the 

 wind and tide, twice the length of the chains by which they ride. 

 The comparative expense of these two modes of lighting is yet 

 to be considered ; and here the advantage is still nuire in favour of 

 fixed lights. The annual expense of the Fleetwood lighthouse, in 

 lighting materials and attendance, amounts to 335/., as appears by 

 the statement of Mr. P. Bidder, resident engineer at Fleetwood, 

 laid before the Lighthouse Committee of the House of Commons 

 in 1845 ; while, on the authority of Captain Washington, R.N., 

 the average annual expense of the floating lights of Great Britain 

 is 1,316/. A reference to the report of that committee augments 

 considerably their average cost. 



In the summer of 1844, a screw-pile lighthouse, serving also as a 

 pilot station, was placed in Belfast Lough, Carrickfergus Bay, on 

 the tail of the Hollywood bank, about a mile from the coast of 

 Down. The depth at low water where the house is placed is 9 feet ; 

 the stratum for a few feet next the surface was coarse sand and 

 gravel, but the soil beneath was tenacious blue clay, and was easily 

 penetrated. The cast-iron screws were 3 ft. 6 in. diameter, and 

 were used with malleable iron piles, 5 inches diameter and 26 feet 

 long, and were sunk into the bank to the depth of 16 feet. The 

 structure is very similar in principle to that at Fleetwood, the only 

 difi'erence being that the house is larger and the lantern smaller, it 

 being only necessary for the light to be visible from a distance of 

 six or seven miles. This lighthouse, from a variety of causes, was 

 constructed at considerably less expense than that at Fleetwood- 

 on-Wyre. Amongst these may be mentioned the sheltered posi- 

 tion, less costly lighting apparatus, cheap labour, and summer 

 weather ; but above all, the desire of the author that his native 

 town should be benefited by his labours. 



Three beacons have been erected by the author and his son for 

 the Dublin Ballast Board, on the Kish bank, the Arklow l)ank, and 

 the Blackwater bank. These have all been put down with the in- 

 tention of placing lighthouses on their sites, 

 should they appear eventually to suffer no 

 change by the action of the sea. All these 

 beacons are similar in form and principle 

 (fig. 7) ; each consisting of a single pile of 

 wrought-iron in two joints, connected by a 

 strong screw coupling, and measuring, when 

 together, 63 feet in length ; their diameter 

 at the surface of the ground is 8 inches, 

 diminishing from thence both up and down. 

 The incompressible nature of the sand off'er- 

 ing considerable opposition to the descent 

 of the pile, screws of only 2 feet in dia- 

 meter were used, and on the top of each 

 pile, when fixed, a ball was placed of 3 ft. 

 6 in. diameter. The screws used for the 

 Blackwater and the Arklow beacons were 

 forged of malleable iron, and turned in the 

 lathe, at great exi)ense ; but that will pro- 

 bably never again be necessary, as they can 

 generally be quite as well made of cast- 

 iron and at mucli less cost. One of these 

 beacons was fixed in June, 1843, the other 

 two in the summer of 1846, and are all 

 standing, though two of them diverge con- 

 siderably from the perpendicular, having 

 been frequently struck by vessels in heavy 

 weather. 



In the summer of 1846, a larger and 

 more important beacon was placed between the Queen's and 



Fig. 7. 



