126 



THE CrvaL ENGINEEU AND ARCHITECT'S JOURNAL. 



LApBit, 



level of the railways ott each side, so as to unite them in one uninterrupted 

 line from London to Berwick, and unite the termini of the different railways, 

 now separated three quarters of a mile or more, into one grand central sta- 

 tion, a little to the west of the ancient Castle. The distance between this 

 station and the present terminus of the York and Newcastle Railway is 3,457 

 feet, consisting chiefly of the space occupied by the bed of the river Tyne, 

 and the steep banks on each side, well known to travellers in descending from 

 Gateshead Fell on the south, and Dean Street on the north, both to be now 

 superseded by the smooth and level surface of the railway, and by a turnpike 

 road running on the same bridge directly under the line of rails. I he steep 

 banks on each side are spanned by stone arches of a very substantial charac- 

 ter, the river and low banks by six metallic arches, all of the same dimen- 

 sions and structure, resting on solid piers and lofty columns of masonry. In 

 the bed of the river the piers are laid on very solid foundations of piles and 

 planking, with concrete, many of the piles 40 feet in length, and driven to 

 this depth through hard gravel and sand till they reacli the bed of freestone 

 rock. Nasmyth's celebrated pile-driver is in full operation here, and with 

 wonderful effect, and has come most opportunely in aid of the work ; driving 

 night and day, at the rate of 60 or 70 strokes a minute, the pile heads being 

 often set on fire by the rapidity and violence of the blows of the ram. Piers 

 laid 2 feet below low-water mark, and raised about 100 feet to the springing 

 of the arches. The arches consist each of 4 main ribs of cast-iron, each in 5 

 segments bolted together, and forming one entire arch 125 feet span, and 

 rising 17 ft. 6 in. in the centre, and the level of the rails on the upper plat- 

 form 108i feet above the level of high-water mark of the Tyne. Depth of 

 the rib 3 ft. 9 in. at the springing, and 3 ft. 6 in. at the crown, with flanches 

 12 inches broad, external ribs 2 inches thickness of metal, internal ribs 3 

 inches. Total sectional area at the crown 644 square inches, which would 

 bear with safety a load of 5,000 or 6,000 tons, and would form, with proper 

 abutments, a strong arch in itself; but for the fullest security, and to prevent 

 the possibility of inconvenience or risk from deflection or vibration, or other- 

 wise, each rib is united at tlie springing by strong malleable iron bars or 

 ties, 7 inches broad and 1 inch deep, of the best scrap iron, and in all 24 in 

 number. The railway is supported above the arch, and the roadway sus- 

 pended from beneath, by hollow cast-iron pillars 10 feet apart, and each 14 

 inches square, through which are passed strong malleable iron circular bars, 

 binding the whole into one stiff and solid mass. The sectional area of the 

 horizontal bars is 1G8 square inches, which would sustain upwards of 4,000 

 tons without breaking, and 1,500 tons with perfect safety, but the whole 

 weight of the bridge will not exceed 700 tons, leaving 800 tons of surplus 

 strength. The railway, which is at the summit level, runs oa a level 4 feet 

 above the crown of the arched rib, and is supported in the middle by hollow 

 cast-iron trough girders resting on the top of the pillars 10 feet apart, and 

 united by longitudinal timbers laid with strong planking. The roadway runs 

 nearly on a level with the malleable iron ties, leaving a space of about 20 

 feet clear head-room. 



In the whole of the work the utmost pains has been bestowed on materials 

 and workmanship, and in making everything complete, the surfaces, which 

 abutt together, being regularly planed or turned, as in machinery ; and, from 

 all the arrangements, the most successful results may be anticipated from 

 this bridge. The cost of the iron work and roadway, by the estimates, 

 jomes to £112,000, and the contracts for the bridge and viaducts to some- 

 hing above £300,000. 



CONWAY BRIDGE, CHESTER AND HOLYHEAD 

 RAILWAY. 



We give the following details of floating the tubular bridge at Conway, 

 on account of their highly interesting characler. Next month we hope to 

 be able to give full particulars of the raising of the tube and the ma- 

 chinery. 



In sight of a large concourse of people, covering the whole space of the 

 suspension-bridge, the towns and walls of the noble old castle, and the 

 fields in the background of the spot on which it was built, the wonderful 

 effort of science, the tube-bridge, was floated at 11 a.m., on the Cth ult., 

 and moved from the piles and slays oil which it was constructed, and 

 fairly brought into the tide-way of the Conway, while its flood-tide was 

 running at the rate of at least two miles per hour. It appeared to float 

 with the greatest ease, and not immersing the six pontoons on which it 

 rested (three at either end) to within at least 3 feet of their decks. The 

 precautions taken by Capt. Claxtou, R.N., to whose sole direction the 

 transporting of this enormous mass was committed, were admirably cou- 

 trived to keep the machine suspended over the fixed piers, to await, as it 

 were, the decision of the engineer as to whether the perilous step of 

 launching into tlie deep (for deep indeed is the river, 12 fathoms at low 

 water) should be proceeded with, or whether the valves should be lifted, 

 and the tube dropped, as it were, again in place, upon ils piers — many cir- 

 cumstances appearing to bear upon that dettrniinatiou ; the strength of 

 the current; the height to which the tide promised by its comparative 

 rising; and the strength of the wind. At about 11 a.m., however, the 

 tide appeared to slacken, and tlie resolution was formed, for all at once 

 the chains and ropes were hove upon, and in ten minutes it had paseJ that, 

 the first Kubicou— gradually but steadily it approached (he site intended 



for it. Mr. .Stephenson, with Mr. Edwin Clarke and Mr. Brunei, accom- 

 panied Capt. Claxton, who directed the proceedings. He used two figures, 

 of large dimensions, Nos. 1 and 2 : when the red side was shown of the 

 former number, a capstan fixed on the road from Conway to the tube works 

 was hove upon ; when the while side was shown the heaving stopped, and 

 a similar operation with No. 2 governed the operations of a powerful 

 capstan (lent by the Admiralty), fixed on the railway on the Chester side, 

 with its rope made fast to the inside of the tube, on that end. In the 

 pontoons three enormous masses of timber, 9.5 feet long by 25 feet wide, 

 and 8 feet deep, bound together by powerful crabs worked by 44 men, 

 hove upon the chains, which had previously been tightened up by a large 

 crab, at which a dozen or more men strained with their utmost efforts at 

 either end on shore, one end of each chain being fixed at the piers of the 

 suspension-bridge, while the other ends were fast to the aforesaid crabs, 

 on the opposite side of the river : on these chains the pontoons appeared 

 to traverse. The western, or Conway end, was pointed first, but did not 

 come quite home afterwards. The eastern, or Chester end, was dropped 

 in after, or while the ebb was making ; but before it reached by about a 

 dozen feet the exact berth, it took the mason-work, and no ellbrt could 

 disengage it. Nevertheless, it was over its bed suUiciently to be landed 

 and bedded up with timber previously prepared from a lower bed, which 

 had been provided in case the tide should fall before the upper bed could 

 be reached. The most extraordinary efforts were made with screws and 

 tackles, no less than four of which latter were at one time applied, besides 

 the Chester side crab, manned by 60 people, while the tide was falling, to 

 overcome the obstacle ; but they appeared to be ineffectual, and Capt. 

 Claxton was heard to give orders for bedding up, which was speedily ac- 

 complished. The barges were then sunk a little, and the noble fabric 

 rested very near the hydraulic presses which are to be used in raising it. 

 Eighty men were in each set of pontoons— one set commanded by Capt. 

 Dunce, R.N., an assistant of Mr. Brunei, and the other set by Lieut. 

 Blatchley, R.N., the crews under them performing the principal work, 

 being sailors from the " Home," of Liverpool. In the tube attending the 

 hawsers, were the officers and some of the crew of the Great Britain. 

 On the top, on the Conway side, Mr. Fairbairn, of Manchester, had the 

 direction ; and on the Chester side, Lieut. Glenny, R.N. The great dif- 

 ficulty to be overcome was apparent — the small space to play in — for on 

 the Conway side it wants 9 inches, by actual admeasurement, of being 

 home, or in place; while on the Chester side, it is fairly jambed against 

 the masonry — so that in fact there were barely 9 inches free in 400 feet. 

 No sooner had the tide fallen sufficiently than the obstacle to the exact 

 fixing in position became apparent to all. The inner pontoon was butting 

 at ils end against and partly on a rock. It took the ground which had 

 been blasted away from the solid rock in consequence of having got a 

 little twisted previously to starling, we were assured full 4 feet. On the 

 11th ult., the tube was again floated by the pontoons, and was finally 

 placed with ils two ends resting upon the shelves of masonry constructed 

 to receive it, prior to its being raised to the elevation at which it is placed, 

 about 15 feet or 16 feet above. The lifting of this enormous mass of iron, 

 which weighs about 1,300 tons, is to be effected by two hydraulic presses, 

 with 18-inch rams, and pumps f of an inch diameter. These pumps are 

 to be worked by steam-engines, which will give a pressure equal to 3 tons 

 on the circular inch, or a total lifting power for each press of 972 tons, 

 which, of course, will be amply suflicient for the purpose. Each press 

 has a lift of 6 feet ; and, as the ends of the tube rise, the masonry which 

 is intended to support them will be carried up from the shelves on which 

 they now rest. 



AUXILIARY STEAM-POWER FOR VESSELS. 



Sir — In consequence of the great extension of railways, and the facility 

 they give for quick transit of goods, they are operating seriously against 

 the shipping interests and coasting trade ; and unless some mode can be 

 adopted by which coasting vessels can be made to compete with the raiU 

 ways, this trade will be completely destroyed, which will be a serious 

 loss to many harbours, and also the mercantile interests of the country ; 

 as railways will obtain not only the light and best-paying goods, but also 

 many of the more bulky articles, in consequence of the want of regular 

 sailing traders. 



I think it would be interesting to many of your readers who feel a deep 

 interest on this subject, to ascertain what has been done in many places 

 by employing small steam-power auxiliary to sailing vessels; and as you 

 have the means of doing so, I have taken the liberty of directing your at- 

 tention to tliis important subject, which many of yourcorrespoudents could 

 easily supply, and auswer such queries as the following :— 



The best system of applying auxiliary steam-power to vessels in the 

 coasting trade, of 150 to 200 tons burden per register? 



A description of any such .' 



Whelher wood or iron preferable, aud the cost? 



The size of engine or horse-power, aud whether applied to screw or 

 paddles? 



The draught of water, &c. &c., and any particulars as to Ihe trade 

 they may be engaged in, and how they are answering? 



