334 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[October, 



Mr. Alexeinder Gordon, the engineer to the Commissioners appointed 

 to carry the phui into effect, is the designer of this building, and who 

 recommended the adoption of cast iron, in consequence of the sugges- 

 tions some years ago of Captain Sir Samuel Browne, and the subse- 

 quent erection of a small light tower on Gravpsend t'ier, by Mr. Clarke. 

 The advantages which iron, when not in contact with sea water, 

 possesses over stone or other materials, is, that upon a given base a 

 much larger internal capacity for dwellings and stories can be obtained 

 with equal stability. The "nature of the material admitting of the 

 plates being cast in large surfaces, there are fewer joints, and conse- 

 quently greater solidity. A system of bonding the plates may also be 

 adopted, which will insure the perfect combination of every jnirt, so 

 as to form one entire mass, and by the facility which such a plan offers 

 for imiting the parts, the best form for strength and stabi ity can be 

 obtained. The time required for the construction of such a building 

 in iron being less than that required for the j)rei)arationof one of stone, 

 would in many instances influence its adoption, and from the compara- 

 tively small bulk and weight of the component parts of the structure, 

 much greater facilities are afforded for transporting and erecting it at 

 its destination. It is a fact worthy of remark that in less than three 

 months from the date of the contract, the lighthouse in question was 

 east and erected on the contractor's premises, and it is the intention 

 of Mr. Gordon, the engineer, to have the light exhibited in Jamaica, 

 on January 1st, 1S42, being six months from the date of ilscominence- 

 nrent. This is a degree of expedition commensurate with the extra- 

 ordinary despatch of the present day, when all operations however 

 great and difficirlt, seem to advance with a celerity which a few years 

 back would have been deemed chimerical. 



The expences of the construction, the transmission to its destination, 

 anil its final erection, will not exceed one-third the cost of a stone 

 building of equal dimensions and capabilities, and in localities where 

 the materials are not naturally produced, but have to be transported 

 from a distance in a fit state of immediate erection, the expence would 

 considerably exceed this ratio. Another prominent feature in the 

 construction of iron lighthouses, &c. is the security fi-om electric in- 

 tUience, the material itself being one of the best conductors of tlie 

 electric fluid, and if proper means be taken to transfer the electric 

 fJuid from the base of the tow er to the sea by means of copper con- 

 ductors, no danger need be apprehended from its effects. 



The lighthouse in question is the first of its kind that has been 

 jiractically carried out, and from its having to withstarrd the destruc- 

 tive hurricanes, which, as well as the frequent earthquakes that occur 

 in the West Indies, it will afford a good example for future practice. 

 The form has been selected as well for strength as for symmetry ; and 

 the arrangement of the lantern and light apparatus reflects the greatest 

 credit on the manufacturer, Mr. Deville. 



The tower is to be founded on a coral rock, a little above the level 

 of the sea, the face of which rock is about 10 feet beneath the surface 

 of the sand, and which will be excavated to receive the base of the 

 tower, resting on and cased with granite, to prevent the natural filtra- 

 tion of the sea water from acting upon the iron. The course of granite 

 upon which the base of the tower rests, is grooved to receive the 

 flange of the lower plates, from which the lightning conductors are 

 continued to the sea. The diameter of the tower shaft is IS ft. 6 in. 

 at its base, diminishing to 11 feet under the cap; it is formed of nine 

 tiers of plates, each 10 feet in height, varying from 1 to | inch thick- 

 ness. The circumference is formed of 1 1 plates at the base, and nine 

 at the top, they are cast with a flange all round the inirer edges, and 

 when put together these flanges fornr the joints which are fastened to- 

 gether with nut and screw bolts, and caulked with iron cement. The 

 cap corrsists of 10 radiating plates which form the floor of the light 

 room, arrd secured to the tower upon 20 pierced brackets, being 

 finished by a light iron railirrg. The lower portion, rramely 27 feet, is 

 filled up with masonry and concrete, weighing about 300 tons, and so 

 connected with the rock itself that it forms a solid core of resistance ; 

 the remaining portion of the building is divided into rooms v\bieh are 

 to be appropriated as store rooms and berths for the attendants in the 

 lighthouse. 



The light room consists of cast iron plates 5 feet high, on which 

 are fixed the metal sash bars for receiving the plate glass, these ter- 

 minating in a point are covered with a copper roof, from which rises a 

 short lightning rod, treble gilt at the point, to attract the electric cur- 

 rent. 



The light is of the revolving kind, consisting of 15 Argand lamps 

 and reflectors, 5 in each side of an eqirilateral triangle, and so placed 

 as to constitute a continuous light, but with periodical flashes. 



In order to preserve as low a temperature as the nature of the cir- 

 eumstances and climate will permit, the iron shell is to be lined with 

 a non-conducting material, such as slate or wood, leaving an annular 

 interstice, through which a constant ventilation will be effected, ani 



bv which the excessive heat will be carried off, or which it will doubt- 

 less be assisted by the evaporation of the sea spray which may ac- 

 cidentally be cast upon it, as it will be placed within (10 yards of the 

 ordinary water level. 



In order to preserve the two lower tiers from oxydation, they have 

 been coated with coal tar, and Mr. (jordon intends to set them in the 

 granite with a bituminous cenrent. The only bracing which has been 

 thought requisite is a few cross ties at each horizontal joint, over 

 which the irorr tongued wood floors are laid. 



'Ihe several rooms are provided with five apertures fitted with oak 

 sashes glazed with plate glass; the ap|)roach to the doorway which is 

 about 10 feet above the level of the sand, will be by means of stone 

 steps, ladder irons are also provided in the event of the stone steps 

 being carried away by a hurric.ine. 



Over the entrance is a large tablet of iron, su[)ported by two small 

 ones, and on them, in bas relief, are the following inscriptions : — 



"Erected A.D. 1842, 



" Under the act 3 Victoria, cap. GG. 



" CosiMrssroNERS. 



' Vice-Admiral Sir Charles Adam, 



K.C.B. 

 ' Commodore Douglas, R.N. 

 • Hon. S. J. Dallas. 

 ' W. Ilyslop, Esq. 

 ' J. Tavlor, Esq. 

 ' l.'on.'M. Mitchell. 



" E. Jordan, Esq. 



" P. Lawrence, Esq. 



" Hon. T. M'Cormack. 



" Hon. E. Panton, Speaker. 



" A. Barclay, Esq. 



'* II. Leslie, Esq. 



" G. Wright, Esq. 



'On the designs and specitrcation of Alexander (Gordon, civil engineer, 

 London." 



' C. Robinson, Engineer, London, 

 fecit." 



And on the side supporters : — 

 " Captain St. John, R.A., Island 

 Engineer." 



The whole of the castirrgs were executed by Mr. Robinson at his 

 manufactory, (late Bramah and Robinson), at Pimlico, and put together 

 in the yard i.f the manufactory prior to their removal for its intended 

 destination. 



The work will be re-erected in Jamaica by means of a derrick and 

 crab from the inside, without the aid of any external scaflolding. 



Arch. R. Renton. 

 Seplemher ■2-2, 1841. 



[We understand that the who'e expence of the lighthouse, including 

 the passage over the Atlantic, and the erecting it on the promontory 

 in Jamaica, will not exceed .£'000, and that the entrre weight 

 of iron of the whole fabric is about 100 tons. The masonry is 

 bein" prepared in this country, as it will be more economical 

 to send it from England than it will be to get the stone and work it 

 irr Jamaica. Three mechanics are also to be sent out with the work 

 to put it together on its destined spot. — Editor.] 



TURKEY. 



The spirit of imorovement which has been of late years exhibited 

 by the Turkish government has not been confined to political and 

 social reforms, but has also been directed to objects of a practical na- 

 ture. In aid of these efforts frequent calls have been made on the 

 talents of our engineers, and some very fine machinery indeed has 

 been sent out to Constantinople. Much of this has been on a very 

 large scale, and we may enumerate saw nrills, musket machinery, and 

 gun-boring machinery. The machinery sirpplied by Messrs. Maudslays 

 for boring brass guns, said to be the finest and most extensive of any 

 in the world, has given great satisfaction. The same firm have lately 

 finished an order for mint machinery, also on a large scale, which has 

 excited great commendation fr'om the completeness of its design, and 

 the beauty of its execution. It consists of two 16 horse power high 

 pressure engines, two pair of large rollers, and two pair of smaller 

 rollers, six cutting out presses, two double draw benches, four coining 

 presses with prreumatic apparatus, and a die sinking press, with two 

 double acting milling machines, ingot moulds, &c. To those who ad- 

 mire this class of machinery, as who does not, the examination of this 

 minting apparatus was highly interesting, uniting as it did all the re- 

 cent improvements which have been adopted in our mint. The 

 Turkish dockyard it must be farther remembered, is directed by ub 

 Anglo-American, and is in a very efficient state, and the public at 

 Constantinople have recently been turning their attei lion towards 

 steam navigation, so that we may look forward for a new market for 

 our machinery in the Turkish empire. To the engineering and min- 

 ing interests ihe progress of this increasing branch of our commercK is 

 of great importance. 



