1843.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



J 43 



ments, nor any horizontal power in the platform, ami that it is the chains 

 only which sustain the structure. In a chain or rope in a pendent curve this 

 cannot he avoided, but in a bridge which consists of curved and horizontal 

 lines, it is clear that the vertical and horizontal forces should be divided, as 

 it is sufficient for the chains in any bridge, in their position of reduced 

 power, to support themselves, the platform and the transit loads ; and, inde- 

 pendently, it is very clear that the horizontal force should not be in the 

 chains to facilitate their destruction, but in the horizontal line, where it 

 cannot act in the direction of gravity, but where it is as essentially useful 

 towards the maintenance of the structure, as are the chains themselves. It 

 may be remarked that this system facilitates the manufacture of bridges, 

 out of the cheapest and most durable materials — it enables their strength to 

 be computed as easily as the contents of a block of marble is ascertained — 

 requires but one lamina of timber for the roadways, and presents but little 

 surface of resistance, therefore the wind cannot affect it, nor is any longi- 

 tudinal trussing required, as in other bridges, whose equilibrium is easily 

 affected by the slightest force, because they rest on their eenres, similar to 

 the logan stone. 



A. Z. 



IMPROVEMENTS IN METAL FOR SHIPS, &c. 



Mr. William Fairbairn, of Manchester, engineer, has obtained a patent 

 for " certain improvements in the construction of metal ships, boats, and 

 other vessels ; and in the preparation of metal plates to be used therein." — 

 They consist in preparing or rolling the iron intended to be used in the con- 

 struction of ships and vessels, by forming at each edge, and the whole length 

 of the plate, a raised border, — or, in other words, the plate is made at each 

 side or edge, where the rivets pass through, something like double the thick- 

 ness of any other part of the plate: one side of the plate being plain, which 

 is to be the outside in the construction of a vessel, the other side having two 

 projecting edges, or borders. The rivet-holes on the plain side of each plate 

 are to be countersunk, so that the head of the rivet may be fiat or flush with 

 the face of the plate ; and in joining two or more plates together, they are 

 not to overlap each other, as hitherto practised, but the plates are placed 

 with their edges together; and behind the two is placed a metal band, bar, 

 or rib, perforated with a double row of holes, to correspond with the holes 

 in the edge of each plate, and the whole are firmly rivetted together so as to 

 form a water-tight joint ; and where greater security or strength is required, 

 the metal bands or bars are made in the form of a T, or with a projection on 

 the back side ; by this arrangement the resistance of a vessel in the water 

 will not be so great, and the plates at the parts where the rivets pass 

 through will be equal in strength to any other part of the plate ; whereas, 

 in those of ordinary construction, the plates are considerably weakened by 

 making the rivet-hoies, as such parts have always been found to give way 

 when the plate itself has remained entire. — Record of Patents. 



IMPROVEMENTS IN CHIMNIES. 



M. Eugene de Varroc, of Bryanstone-street, Portman-square, has ob- 

 tained a patent for " apparatus to he applied to chimnies to prevent their 

 taking fire, and for rendering sweeping chimnies unnecessarg." — This inven- 

 tion relates to the application of reticulated metal surfaces, at the com- 

 mencement, or near the entrance, of the chimney, in order to prevent the 

 passing of the flame, and also to intercept the soot. The apparatus consists 

 of two cylinders of wire-cloth, one within the other, but so constructed that 

 the surfaces of the two cylinders touch, or are in contact with eacli other. 

 The inventor prefers to make the cylinders of wire-cloth, having sixty -four 

 holes to the square inch, or closely perforated metal plates may be employed, 

 but such will not be found as useful as wire-cloth. The cylinder, which is 

 mounted upon an axis, is fixed in the chimney, as near the fire as convenient, 

 the flue or chimney being so constructed as to prevent any passage for the 

 smoke but through the double-wire cylinder, the wires forming the reticu- 

 late, or open work, of one cylinder, being made to cross those of the other 

 cylinder. By this arrangement the flames and soot will be prevented from 

 passing through the cylinder ; but there will be sufficient draught through 

 the cylinder for the fire, and the chimney beyond the apparatus will not be 

 coated with soot, the same being deposited on or about the apparatus, which 

 will require to be brushed off every morning, and, if desired, the cylinder 

 can be turned partially round, so as to present another part of its periphery. 

 A modification of this apparatus, composed of a number of perforated plates, 

 and arranged in a rectangular form, is shown, as being applied to the chim- 

 ney of a steam-engine boiler ; in which case there are brushes constructed 

 for clearing the same occasionally from soot. — Ibid. 



A FIRE ESCAPE. 

 A correspondent suggests the followiug simple plan for a fire escape : — 

 1st. Two ropes of 40 feet in length, each attached to a small chain also 

 40 feet in length, the end of each chain armed with a spring hook. 

 2nd. A stout sack of incombustible material (like the fire-proof dresses), 



open mouthed, with a metallic rim, about four feet deep, and wide enough 

 to hold two persons, with two spring books on the opposite sides of the 

 metallic rim, and connected therewith by a small chain of 9 inches long. 



These articles should be brought to the spot on the first alarm of tire by 

 a police constable. One rope and chain should be carried into the house 

 next adjoining on the right of the one on fire, and while the rope is held 

 fast, the chain should be dropt from the upper window till it touches the 

 pavement ; and the same should be done with the other rope and chain from 

 the house on the left side ; the two chains should then be hooked together 

 by the policemen or neighbours. The escape sack should immediately be 

 attached to the centre of the combined chains, and be rapidly drawn up to 

 any window where a person may appear in danger. The moment the indi- 

 vidual has got into the sack, one rope must be eased off, so as to allow the 

 other rope to become perpendicular, when the rescued party may be taken in 

 at a lower window of the neighbouring house, or lowered to the pavement ; 

 the rescuers giving the rope a half turn round a bed post, so that the lower- 

 ing may be effected discreetly. It need scarcely be added, that this operation 

 may be repeated several times in a minute, if there should be more indi- 

 viduals to be rescued. The sack, when manufactured, should be steeped in 

 some solution prepared to resist combustion, and care should be taken that 

 the ropes are not unnecessarily exposed to flame. 



FLAX MILL AT CASSANO, IN LOMBARDY. 



A flax and power loom mill has been established at Cassano, which has ex- 

 cited a good deal of attention in Italy. It belongs to Messrs. Battaglia and 

 Co., and the works were erected by Mr. Albano, C. E., of London. The mill 

 is for flax and hemp, and is divided into three compartments, containing up- 

 wards of 8000 spindles, set in motion by a water-wheel worked by the Adda, 

 and 16 ft. in diameter, by 21 ft. or 24 ft. broad. This wheel is of cast iron, 

 except the floats, which are of sheet iron, and the whole weighs 36 tons. 

 To this wheel are attached apparatus for governing the velocity of the 

 machinery, lifting weights to the upper stories, and working fire-engines. 

 In the factory is also included a steam drying apparatus. Altogether the 

 arrangements of the establishment and the adaptation of the machinery are 

 looked upon as conferring great credit on the engineer, and has given great 

 satisfaction to all parties concerned. 



THE THAMES TUNNEL. 



This important undertaking was opened for foot passengers on the 25th of 

 March last. Thus, after many years of anxiety and difficulties, perhaps 

 without parallel in the history of great Public Works, the practicability of 

 forming a thoroughfare for carriages and foot passengers under a deep navi- 

 gable river, and without interruption to the navigation, is proved and exe- 

 cuted. The obstacles, which have from time to time impeded, and all but 

 stopped the progress of the Tunnel, have been numerous. The work was 

 commenced in 1823, but was stopped in 1828, by an irruption of the 

 Thames. From that time to the spring of 1S35 no progress was made. In 

 this year, uuder the sanction of an Act of Parliament, the Treasury allowed 

 the Exchequer Loan Commissioners to advance, out of the grant voted for 

 Public Works, the money necessary to complete the Tunnel ; and it was 

 again commenced and has been continued with few but inevitable interrup- 

 tions and delays to the present time, when, as the Directors have stated, it is 

 securely completed, and is now thrown open to the Public as a thoroughfare 

 for foot passengers. The two roadways for carriages under the river are also 

 perfectly completed. From its commencement to the present date there 

 have been but 11 years within which the excavation could be carried on. 

 And during this time, for nearly two years or ninety-nine weeks, the works 

 were suspended from circumstauces beyond the control of either the Di- 

 rectors or the Engineer. The work has been in fact executed in about 9 years 

 of actual work, at a cost of about £446,000, including property and ex- 

 penses of every kind, with the particulars of which the Proprietors have 

 been accurately and annually acquainted. The actual Tunnel of 1200 feet 

 was executed in eight years. The Carriage-way descents are now alone 

 wanting to complete the work. They are susceptible of being contracted 

 for in the ordinary way. 



The Nelson Monument.— The whole of the leaves, roses, and parts of the 

 Corinthian capital, to be placed on Nelson's monument, Trafalgar-square, 

 have now been cast at the foundry in the Royal Arsenal, Woolwich, with 

 the exception of four volutes. The latter ornaments are most elaborate in 

 their detail, and some idea of the difficulty of making a casting in one piece 

 may be formed, when it is stated that the mould, before it is put together, 

 has to be arranged from about 301) distinct parts, and great doubts are enter- 

 tained of the artist, Mr. Clark, being able to cast the requisite quantity of 

 metal in the peculiar form of this beautiful and graceful ornament. He is 

 resolved, however, to make the attempt, and confidently anticipates being 

 able to complete the undertaking with from 10 to 13 ewt. of brass. Had the 

 usual mode been adopted the casting could not have been effected with less 

 than about 40 ewt. of metal. 



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