Volltext Seite (XML)
]S(Jf4,l , a | THE CIVIL ENGINEER AND ARCHITECT’S JOURNAL, 293 THE RIVER DEE LIGHTHOUSE. Fig. 1. We are glad that the ingenious inventions for constructing light houses on sands, which we were among the first to recognize, may now be considered as fully established in the catalogue of engineering resources. It is by such applications of science to the useful arts that engineering acquires and extends the strong hold, which it is evidently taking on the public mind, and the importance which is being communicated to its professors. We are fortunately a very practical people, and nothing can be more welcome than those exer tions of ability conformable to our disposition, while it need scarcely be said that he who invents a new machine adds to the power and wealth of our common country. Thus in the instance before us, pro perty is to be secured, life preserved, and commerce extended by the improvement of our harbours, and by the detection and prevention of marine risks. The construction of Lighthouses on sand-banks is a modern inven tion, and has already been successfully adopted, as shown by drawings in our Journal, at Fleetwood, and the Maplio Sands in the Thames. Both these constructions were erected by the aid of Mitchell’s Patent Screw Piles, to form the foundation. We have now to record another lighthouse erected under the direction of Messrs. Walker and Burgess, for the Corporation of the Trinity House, at the point of Air, in the county of Flint, at the mouth of the River Dee, a short account of which was given in the Journal lor last May, page 20S; the founda tions are upon a different plan to those before erected, as in stead of serevv piles, cylinders were sunk in the sands to form the foundations, as we shall proceed to explain. At low water the sands are dry, when the workmen were enabled to proceed in their operations, by first sinking a slight cylinder of plate iron 4ft. Gin. diameter through the sands to the depth of 4ft. ; within this cylinder another cylinder of cast iron 3ft. 9in. diameter and 9ft. long was gradually lowered through the sands by excavating the sand from the inside by the aid of an instrument well known to well-sinkers, called “A Miser;” great precaution was taken to keep the cylinder perfectly perpendicular as it was lowered ; within a few inches of the bottom of the cylinder a cast iron flange, 3 inches wide, is cast upon the inside for the purpose of receiving the cast iron disc No. 84.—Vot. VII,—August, 1844. Section of Cylinder and Pillar. shown in fig. 3: when the cylinder was sunk to the depth of 12 feet, a _Fig. 2. hollow cast iron pillar 13 feet high and 1 foot external diameter below, was set in the centre of the cylinder, the foot resting upon the disc at the bottom, as shown in fig. 2; when the pillar was placed in its proper position the sur rounding space was filled in with con crete, and on the top were laid large stones about a foot thick, the whole forming an immoveable foundation of 10 tons in weight. There were nine of these cylinders, eight at the angles and one in the centre, sunk through the sand, making together a total weight of 90 tons to receive the lighthouse. On the top of the pillars are cast sockets for the purpose of receiving the bent or curved pillars, as shown in fig. 1, and which werealso cast hollow with sockets to receive the inclined pillars upon which the building was erected. The piles are firmly tied together by two tiers of horizontal ties all round the eight sides, and again by diagonal ties from the centre post to each of the an gular posts. The upper part of the edifice is inclosed with Palmer’s patent corrugated iron plates, with a space on the inside, and lining boards, which form a living room for the attendants; and the conical part below a small kitchen and water closet. The lan- thorn above is constructed of gun metal in a very superior manner. The whole of the iron work was prepared by Messrs. Gordon and Co., engineers of Deptford, under the immediate direc tion and superintendence of Messrs. Walker and Burgess. During the construction of the light house, and since it has been finished, it has been exposed to some severe gales, which it has withstood with remarka ble firmness. ARTESIAN WELLS AT SOUTHAMPTON. During the meeting of the Royal Agricultural Society, Dr. Buck- land delivered a lecture on Artesian Wells, and in particular on that which is now in progression at Southampton. Though uncompleted, it is a work of immense magnitude, vying with the great well at Gre- nelle, by which Paris has been lately supplied. The depth of the Southampton well is at present 1,30U feet .The shaft descends through 78 feet of alluvium, 300 feet of clay similar to the London clay (which is a general substratum in the Southampton basin), and through an other 100 feet of plastic, day, before it reaches the chalk, through which it descends 100 feet still further. Tlius from the surface a well has absolutely been built downwards nearly 570 feet, and under such difficulties from irregularities in the strata that four iron cylinders have been placed in points where no attempt at masonry could have proved successful. Not the least singular part of this work is the manner in which this underground well has been built from the sum mit level downwards “ into the very bowels of the land.” This is a matter, however, which it would be tedious to describe; suffice it, therefore, that after reaching a depth of nearly GOO feet, the opera tions of the masons were suspended, and the boring-rods were brought into operation, and employed until, through their instrumentality, the contractors have reached a depth of 1,300 feet. As might he ex pected, the supply of water is already abundant. It now rises within 40 feet of the surface, and by the aid of powerful steam-engines no less than 55,000 gallons a day are literally poured into the town of Southampton. It is expected that the water will soon rise to the surface, when the supply will be immensely larger than even this.— Hull Packet. 25