8-2 



THE CIVIL ENGINEER AND AIlCHITECl^S JOURNAL 



[March, 



with stone, and founded on concrete. On account of the flatness of 

 the bed of the river, they are projected forward on each side, so as to 

 concentrate the stream in the centre of the river. By reference to 

 the drawings it will be seen that the cornice of the abutments and 

 piers follow tlie inclination of the roadway, which we consider an 

 imj)rovcment in the architectural effect on the ordinary mode of 

 making the cornice and parapet horizontal, as at London, Waterloo, 

 and otlier bridges. 



We will now proceed to describe the construction of the arches. 

 It will be observed that at the springing of the ribs the abutments 

 are splayed or inclined to an angle of GG deg., and formed of solid 

 masses of stone, on the face of which oval recesses are sunk to 

 receive the abutment plates, and are made a little larger, to prevent 

 the vibration of the bridge splitting the stone off the edges. The 

 abutment plates are of cast-iron, in two pieces, as shown in figures / 

 to 13, wliich were firmly bedded on to the stone with Pouitly cement. 

 These plates form a socket for the reception of other plates bolted on 

 to the ends of the ribs. They were firmly connected together, and 

 the joints filled in with an iron cement, composed of 10 parts of cast- 

 iron filings, '2'5 of sal ammoniac, 1 '8 of sulphur, and 225 of metal 

 dross. All these were in fine powders, carefully amalgamated, and 

 mixed with only enough water to bring them to a good consistence. 

 The weight of each under plate is about 8501bs., and of the upper 

 plates r2201bs. 



In order to unite the firmness of iron with the elasticity of wood, 

 and to insure both against the ravages of the weather, while light- 

 ness and cheapness of construction are equally consulted, M. Polen- 

 ceau has adopted a peculiar form of rib, which has been called, from 

 its shape, the " tubular rib." Each rib is formed in 22 lengths, and 

 composed of two separate cheeks of cast u'on, bolted together, wiih 

 nine thicknesses of timber inside, as shown in figure 19. The inter- 

 stices between the timber and iron are filled in with a composition 

 of two parts of Seyssel asphalte, and one part of gas tar, which also 

 forms a capping on the top of the ribs. In filling in the asphalte, the 

 ribs were heated by means of porlablc furnaces, so that an opportu- 

 nity was afforded of ascertaining (he extreme expansion of the metal. 

 The length of the ribs were of four kinds — outer and inner end 

 pieces, and outer and inner middle pieces, varying in size, but were 

 about 13 feet long on the average, and weighed about 2,8001bs. To 

 insure their strength, each half rib was subjected to a double proof, 

 first by suspending it by a fulcrum at each end, and then laying on 

 it 40 tons ; and again, by dropping a ton and a half on the middle, 

 from a height of 1,2, 4, and 6 yards; these lengths fit into each 

 other, and are fastened together by screw-bolts and iron keys, as 

 shown in figures 16 and 17. 



Each arch is composed of five ribs, connected together by means 

 of cross ties, bolts, and braces, as shown in figures 2 and 3, and more 

 at large at figures 17 and 18: upon these ribs are placed the rings 

 which carry the superstructure ; they vary in size and weight, accord- 

 ing to their position. Some of the larger are 10 feet diameter, and 

 a ton and a half in weight; they are united to each other by bolts at 

 their circumferences, as shown in figures 14 and 15. By reference to 

 figure 19, it will be seen how the lower part of the ring rests upon 

 the ribs; and, by figure 4, how the upper part carries the longitudi- 

 nal bearers : these rings are again connected transversely, by means 

 of bolts across the arch. They required considerable care in setting 

 them, on account of the difference in the size of the arches. Some 

 of them were found too large, and others too small. 



The longitudinal bearers or girders consist of two flitches of oak, 

 bolted together, as shown in figure 4: upon these are laid the trans- 

 verse bearers or joists of oak, which are notched or calked, and bolted 

 down ; upon the joists are laid two thicknesses of planks, breaking 

 joints over each other. The lower planks are of oak, and the upper 

 of deal ; over these are laid the road materials, and on the sides are 

 flitches of timber, forming a curb and gutter to the roadway ; the 

 footpath is also formed of oak plants, raised on longitudinal bearers, 

 as shown in figure 4, with a slip of iron let in flush, the whole 

 length, and iron guards at distances, as shown in figure 4. The 

 exterior of the footpath is converted into a cornice, an iron sunk 

 fascia, being laid over the face of the lower longitudinal bearer, and 

 on the ends of the joists, an iron capping, forming a modillion, witha 

 moulded capping also of cast iron, and the upper part formed into a 

 fascia with a bed molding under the edge of the footpath, the whole 

 having a pleasing effect, as shown in figures 4 and 5. The plankings 

 of the roadway were well rubbed over with tar, and all the joints 

 carefidly filled up with sand, and then rubbed with a mixture of 

 equal parts of vegetable and gas tar. The material of the road is 

 composed of while chalk stones and pebbles, the size of walnuts, 

 and the whole surface of the roadway and footpaths finished with 

 asphalte. On each side of the bridge, to protect the footpath, is an 

 iron railing, with bars 7 inches apart. All the iron work of the 



bridge is painted with an iron grey colour, of M. Polenceau'.s 

 invention. 



We have endeavoured to explain the construction of this bridge in 

 the best manner we are able, and for the better understanding of its 

 details, we refer the reader to the drawings and references which 

 will be found to contain the dimensions of most of the timber. 



We are principally indebted for the drawings to our foreign con- 

 temporary, the " Algemeine Bauzeitung." We wish the editor of 

 that publication would be as generous in acknowledging the numerous 

 articles that have been copied by him from this journal. 



GLENARM HARBOUR. 



"Tlie chief ruler or slnlesman llial will be nble tnfcirm Hsylum-haibiiursi 

 on tlie unsheltered and dangerous parts of tlie coast, mid will also cause 

 to be marked or beaconed, by the erection of ffianile lowers, the danger- 

 ous rocks, the shoals, and the reefs which surround the shores of these 

 kin<(doiiis, thereby giving; safely and secuiiiyto the mariner in lime of 

 teni|iest and storm ; also saffly o the floiling wfaltli of these realms, and 

 the colonies ihereunlo belonging ; also lessening tlie wail ol the widow 

 and the orphan ihroughi'Ul this niaiiiime land — will not only receive Ihe 

 blessings of future generations for thee iiiion of these woi ks of mercy . 

 tfnding so much to the preservation of life and property, but will also 

 increase, to a great ex'enl. Ilie wnnllh. the [lower, and prosperilv of the 

 whole empire." — Bald's Evidence on Harbvuis^Public Works— Ireland. 



Beport o/WilliamB.\ld, Civil Engineer, F.R.S.E. & M.R.I.A., &c., 

 on the erection of a Pier, and formation of a Harbour in Glenarm 

 Bay, in the County of Antrim, Ireland. 



The Bay of Glenarm, where the proposed Pier is intended to be 

 erected, is situated on the north-east coast of the county of Antrim, 

 bordering the North Channel. The bay is about half a mile in 

 length, and three furlongs in breadth ; containing an area of about 

 120 acres, and possessing a very considerable depth of water: four, 

 five, aud six fathoms. The bottom consists of clay, and is well known 

 to be excellent holding-ground to all classes of ships. At the head 

 of Glenarm Bay is situated the town of Glenarm, and the land sur- 

 rounding the bay rises to a considerable elevation, and protects it 

 from the prevailing southerly and westerly gales. This bay is, how- 

 ever, open to the channel sea from the north, north-east, east, and 

 south-east; but the greatest run of sea into it is from tlie north and 

 north-east. The Bay of Glenarm lies nearly opposite the entrance to 

 the Clyde, oft'ering very great facilities to commercial intercourse 

 with all the towns situated on the west of Scotland ; viz., Glasgow, 

 Ayr, Greenock, &c. &c. It is distant from Lame 10 miles, and from 

 Portrush nearly 50 miles ; so that, in an extent of GO miles of coast, 

 there is no harbour, either artificial or natural, to afford protection to 

 foreign traders, coasting vessels, or even to the smallest description 

 of fishing craft. These reasons alone are sufficient to prove the 

 great utility that would be derived from the erection of a harbour in 

 Glenarm Bay ; and it would, also, give shelter and security to a 

 great portion of the floating wealth belonging to the Clyde, the port 

 of Liverpool, the colonies of North America, and the West Indies, 

 which would pass through the Irish Northern Channel. Besides afford- 

 ing an asylum for vessels overtaken by storm, it would give a port 

 to the whole of the central portion of the county of Antrim, consist- 

 ing of large districts of country highly cultivated, and producing 

 great quantities of grain, and cattle of all kinds, and which could be 

 clieaply exported, by means of a harbour at Glenarm; and, also, the 

 valuable facility of importing into the country all the necessary arti- 

 cles of merchandize. Glenarm harbour w-nuld become the port to an 

 extent of country containing not less than 400 square miles, also to 

 the whole of the fertile interior country adjacent to the large and 

 populous town of Ballymena, distant only 12 miles; and it would 

 offer a ready means of direct commercial intercourse with the manu- 

 facturing and maritime districts of the Clyde in Scothind, both by 

 steam and sailing vessels ; and which would, in a very short period, 

 create and augment the trade of the country to a very great extent. 

 The Portrush and Derry steamers to Liverpool, touching at Glenarm, 

 would establish a trade of vital importance to the merchants of Bal- 

 lymena, particularly those engaged in the export of pork, butter, 

 provisions, and liiien cloth. The exportation of limestone from 

 Glenarm to Scotland, and the importation of coal in return, would 

 form a very lucrative and highly beneficial branch of trade between 

 the conntiies. At present there is not mure than about 6,000 tons 

 of limestone exported, and only 1,000 tons of coal imported. There 

 can be no doubt but the importation of coal would greatly increase, 

 both for burning lime, and working the steam-engines and machinery 

 in progress of erection at Ballymena and Brnughshane, when the 

 facility of procuring this necessary article from Britain is attained, 

 by the construction of a harbour at Glenarm. 



