182 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Junk, 



comfortable residence for the light-keepers, whilst affording you a steady, 

 bright, uniform light, 45 feet above mean-sea level, — ranging over an eight- 

 mile horizon, visible 10 miles from a coaster's deck, and freed from those 

 breaks of brilliancy attending the offing passage from reflector to reflector, 

 by being fitted with a light of ' Dioptric' order. Foggy periods are provided 

 for by a self-acting deep-sounding bell, tolling three strokes of five-second 

 intervals, at one minute pauses ; and tide-time for vessels of 12-feet draft, is 

 denoted by 2 black halls being kept upon its flag-staff until 12-feet ceases 

 upon the straight course, right up ; at the same time, however, denoting 17 

 feet up through the buoyed channel ; and vessels requiring a Wyre pilot will 

 be understood at this lighthouse, if showing a weft at the peak, besides their 

 pilot-jack at the mast-head ; whence, a pilot-jack will also be hoisted until 

 she is provided. The Wyre pilot-boats are of sloop and yawl rig, with black 

 bottom, while top-sides and black streak, with her number and the letter F 

 on the mainsail. Tlicir cruising ground extends from Formby Point to Haver- 

 ing Point of Duddan. 



ELEVATION OF WYRE LIGHTHOUSE. 





REFERENCE. 



A, Marl formation ; the screws are 10 feet below low water mark. 



B, Sub-stratum of sand. 



C, Low water equinoctial springs. 



D, Low water ordinary tides, 2 feet above ditto. 



E, Ditto neap tides, 9 feet ditto. 



F, Half-tide level, 15 feet ditto. 



G, High water neaps, 21 feet ditto. 

 H, Ditto ordinary tides, 28 feet ditto. 

 J, Ditto, equinoctial springs, 30 feet ditto. 

 K, Underside of platform, 45 feet ditto. 



Centre of the Dioptric 

 Light in Lanthem 60 feet ditto. 



.SPECinc.iTiON of the abort Screw Pile Lighthouse, erected on the north- 

 eastern lorn-water spit of North Whaif Bank, at the entrance of the 

 Wyre Navigation, the structure being supported upon, and secured to, 

 the bank with Mitchell's Patent Screw Piles, of "ifeet diameter. 



The foundation of the building is formed of seven screw piles, six 

 of which are the angles of a hexagon, about 46 feet in diameter, and 

 the seventh pile stands in the centre of the figure. 



The heads of all the outer piles have an inclination inwards, by 

 which the diameter of the frame-work connecting the top of the 

 columns, and upon which the house stands, is contracted to about 27 

 feet. Each screw pile is formed of a malleable iron shaft 15 feel long 

 and 5 inches diameter. 



On each pile a 3-foot screw is firmly keyed near its lower ex- 

 tremity, beneath which is placed a large drill or opening bit. 



At the upper end of the shaft is a screw of 18 inches long and 2 

 inches diameter, for drawing down and screwing the wooden column 

 to the iron pile, which latter stands about 5 feet out of the ground. 



The columns are thus prepared ; — seven logs of Baltic tiinber are 

 selected, of the largest and best quality ; the centre one is 5G feet in 

 length, all the others are 4ti feet. 



The pedestals rise about a third of their height, and the remainder 

 of the shafts are rounded, both for appearance and as lessening any 

 vibration from the action of the sea. 



An openins in the lower end of each column is then made of 5 inches 

 diameter, and to the depth of about 8 fee^, by boring in the manner of 

 a water-pipe ; strong iron hoops are then driven upon it, hot, the first 

 about 8 feet up, the second about 4 feet, and the third at its lower ex- 

 tremity. 



This hooping will give to the column greater strength than it origi- 

 nally possessed, especially as the wood removed by boring is the 

 weakest in the tree, and adds scarcely anything to its actual strength. 



The column being raised perpendicularly above the iron pile, the 

 end of the latter is introduced into the opening prepared for it, and 

 which has been made to fit accurately upon it; when the top of the 

 pile has reached the end of the cavity, screwing on (by capstan), the 

 foot of the column will be inserted in the bank about 3 feet ; the wood, 

 when wet, will clasp firmly on the iron, but, as an additional security, 

 the internal screw attaches the two together. 



The framing upon which the house stands is firmly secured round 

 the centre column, and to the heads of the outer ones, by means of 

 cast-iron capitals let down over the heads of the columns, the capitals 

 being cast hollow for the purpose ; to the abacus of these the top 

 framing is secured with screw bolts passing down through the wood 

 and iron, having nuts on the under side, all boring or cutting into the 

 main support of the building being thus avoided, and the adjacent parts 

 of the framing are bound together by wronght-iron straps and knees; 

 the beams which radiate from the centre to the heads of the outer 

 columns are 12 inches deep by 7 inches wide, and those which comiect 

 the head of the outer columns, 12 inches by 4. 



To give lateral strength to the building to resist the effect of heavy 

 bodies drifting against it, twenty-four angle braces from round iron of 

 li inch diameter are applied, as shown in the plan, by which a resist- 

 ing power equal, at least, to 35U tons, is presented in every direction ; 

 these braces are secured at the top to trusses cast with the capitals, 

 and beneath to strong wrought-iron bands with projecting bolt holes ; 

 by these means boring into the columns is again avoided, the braces 

 are keyed up at their crossing, as shown in the plan. 



The light-keepers' house, which is hexagonal, is in diameter from 

 angle to angle 22 feet, and 9 feet in height. 



The centre column rises to the base of the lantern, which, with the 

 roof, it assists to support, giving great additional stability to the whole 

 structure. 



The corner-posts of the house are 7 inches by 6, all remaining studs 6 

 inches by 4, beams of roof 9 inches by 5, and all outside planking, to- 

 gether with floor and roof of house, is 2 inches thick. 



The house has an outside door and three windows, and is divided 

 into two apartments, one liaving a fire-place and the floor tiled ; the 

 walls and ceiling of both apartments are lathed and stuccoed. 



The lantern, which is 12 sided, is 10 feet in diameter, and in height 

 to the top of the windows 8 feet, by which the lights are raised above 

 the highest spring-tide level about 31 feet, or 44i above half-tide 

 level. 



The lights (in this case of dioptric order) show throughout the 

 periphery, and the roof is covered with strong sheet iron; (a lighten- 

 ing repeller and conductor, of course). 



The light-keepers' house is covered with sheet lead, and a light 

 iron railing is carried round the top of the building and the platform. 



60, Pall Mall, London, Henry Mangles Denuam. 



Jan. 3), 1840. 



