1844.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



177 



THE IRON ROOF 



AT THE BRICKLAYERS ARMS* STATION OF THE DOVER AND CROYDON 

 RAILWAYS. 



ClTilh an Engravini;, Plate VII.) 

 Reference to the Engraving. 



Fig. 1. Section of roof; and Fig. 2. Girders or bearers, both figures 

 drawn to a scale of \ in. to 1 ft. Fig. 3. Parts at large, drawn to a 

 scale of \h\n. to the foot. A, King head, with ridge piece over. 

 A B, Skylight. B, Flashing piece foot of skylights. C and D, Abut- 

 ments of stays at the principal. E, Foot of principals, with half of 

 a gutter, and a shoe. F, Abutment plate of stays, showing the 

 connexion of the feet of the two stays and the tie rods. Fig. 4. Sec- 

 tion of principal rafter. Fig. 5, Section of stays, D F, and C F. 

 Fig. 6. Plan of station. 



In our last month's number we mentioned that, notwithstanding the 

 accident, which had destroyed a considerable portion of the roofs of 

 the sheds, that tlie station would be opened on the 1st of May, the 

 day appointed ; this was realized, by the spirited exertions of the sub- 

 contractors for the roofs, Messrs. Fox, Henderson and Co., of the 

 London works, Birmingham, and the indefatigable energy of Messrs. 

 Grissell and Peto, the contractors for the whole of the works of the 

 station. 



In the annexed plate fig. 6 is a plan of the station which sufficiently 

 explains the general arrangement. The arrival shed is paved with wood 

 and the platforms laid with the Seyssel Asphalte in a very superior 

 manner; the Colonnade columns are of the Tuscan order, and support 

 a heavy entablature, the roof over the booking offices is covered with 

 large Italian tiles, and the front of the building is in the Italian style 

 with massive iron gates in each of the openings opposite the ends of 

 the rails. The roofs which cover the arrival and departure platforms, 

 rails, and carriage shed, extend in length 405 ft. by 157 ft. 6 in. wide. 

 The space is formed into 3 divisions with iron roofs spanning each 

 which it is our present object to explain. 



The roofs are of a remarkably light construction, but by a judicious 

 distribution of the material ; they have been found, upon actual experi- 

 ment hereafter reported, to be of ample strength. Fig. 1 shows the 

 framing of the roof, one half of one span is only shown as the other half 

 is but a repetition, the total span is 52 ft. G in., and the rise above the 

 springing at E, is 11 ft. and above the centre horizontal tie bar 9 ft., 

 the framing of the principals or trusses shown in fig. 1 are placed 6 ft. 

 4 in. apart from centre to centre without any intervening rafters, the 

 coveringaswillbepresently explained is laid uponthis framing. There 

 are 195 pair of principals ; each may be divided into five distinct 

 members. (1) The two rafters A E; (2) the two outer tie bars, 

 E F; (3) the central tie bar, F F; (4) the two suspension bars, 

 F A; and (5) the four struts, F D and F C. The rafters are com- 

 posed of two wrought-iron bars A E, each the whole length of one 

 side of the roof, and are 2f inches deep by -nr thick ; between these 

 two bars, a flitch of deal 3 in. deep by If thick (four pieces are got 

 out of a 2J inch batten) which projects below the iron work and 

 forms a bead as shown in fig. 4, these iron bars and deal are bolted 

 together with iron bolts 15 inches apart; the deal not only stiffens the 

 rafters, but aflbrds a nail hold for securing the boarding, the rafters 

 abut at the top on to a cast iron king head as shown at large at A, fig. 3, 

 and at the foot they abut on iron shoes to which they are bolted as 

 shown atE., these shoes are merely bedded on the wall or girders and 

 are not in any way bolted down, this allows for the free expansion of 

 the metal. The suspension bars A F, and central tie bar F F, are 

 of wrought iron 2 inches deep by | thick, and the outer tie bar is 3 

 in. deep by f thick ; the struts C F and D F, are of cast iron 5 ft. 

 6i long of a section as shown in fig. 5, three inches diameter in the 

 centre, and two inches diameter at the ends, the ends of the bars 

 it will be seen by reference to fig. 3, A, C, D, and E., p;uis in between 

 the two iron bars of the rafters, and are there rivetted together by 

 f rivets; the ends of the two tie bars at F, and the suspension bar 

 are first secured by means of wrought iron cheeks with two | 

 and i inch rivets to each end as shown at F, and over these is a 

 cast iron abutment piece which clips the wrought iron cheeks, and 

 allows the ends of the two cast iron struts to pass between ; a | inch 

 nut and screw bolt is then passed through the eyes and secures the 

 whole together; it should be here observed that these struts together 

 v»ith the abutment pieces, are all made alike so that it makes no 

 difference whether the diagonal struts be for either the right or 

 left hand abutments — at the top and under the skylights, there are 

 i wrought iron stay bolts between each pair of rafters which cross 

 each other, and give great stiffness to that part of the roof. 



No. 81.— Vol. VII,— May, 1844. 



Between each pair of principals is a skylight, 6 ft. 3 in. wide and 

 4 ft. 2 in. long, of cast iron, A B, Fig. 3, the bars are 2 in. deep and 

 1 in. wide, across two rabbets, and between each skylight is a cast iron 

 gutter 2^ in. wide and 2i in. high ; the top of this gutter is secured 

 by a bolt to the king heads, and at the foot by an iron stud bolted to 

 the principal : on each side of the skylights there is a rabbet cast 

 which turns down into the gutter just described, and at the foot are 

 cast iron flashing pieces, which are overlapped at the top edge by the 

 skylight. Over the top of the skylights is a ridge piece, of cast iron, 

 as shown at A, in length of about 5 ft. ; each end has a fillet cast on the 

 top, these ridge pieces leave a space between the ends, over which 

 is fitted a cast iron ridge capping with a fillet on the underside of the 

 ends so as to clip over the fillets cast on the ends of the ridge pieces, 

 and in the centre is a boss with an eye which passes over the end of 

 a bolt eye cast on the top of the iron king heads, and there secured 

 by means of a key passing through the eyes as shown at A fig. 3. 



By a little attention to the description of the construction, it will 

 be seen that although the parts are put together with great simplicity, 

 considerable judgment has been bestowed upon them to allow for 

 the free expansion and contraction of the metals, and at the same 

 time to give stiffness to the several parts. 



The covering of the roof consists of 1^ inch boarding, (out 

 of one-cut battens,) planed, grooved, and tongued with hoop iron, 

 and nailed down to the principal rafters ; they are laid longitudinally, 

 and are stiffened by plates of fender iron 4 in. wide by ^^t'ls. nailed 

 on the top of the boarding i n a diagonal direction: the external cover- 

 ing is of queen's slating ; the gutters between the roofs at the eaves 

 are of cast iron, as shown at E, the joints of which are secured with 

 iron cement. The feet of the principals, as we before stated, are se- 

 cured to iron shoes, which are of various forms, either for bedding on 

 the walls or the iron girders. The roof is supported on cast iron 

 girders, as shown in Fig. 2, of an elliptical form; the centre is 12iin. 

 deep, and the ends 2ft. 8 in. ; they are let into grooves in the stand- 

 ards over the iron columns, and there secured longitudinally by iron 

 bolts. The distance between the columns is 25 ft. 4 in. from centre to 

 centre ; the standards above the columns are 6| in. square in the 

 middle and Sin. square at the biise and top, and are 2 ft. 8 in. high ; 

 they are let into a socket cast on the top of the column. The columns 

 are 13 ft. high and 6i in. diameter at top, and 8 in. at bottom : they 

 stand on iron bases 2 ft. square and 4 in. thick, bedded on brick piers 

 3 ft. square, taken in all cases down to the gravel; 12 columns are 

 cast hollow and form pipes to convey the water from the gutter to the 

 drain. 



The carriage shed and engine house have a similar roof, as just de- 

 scribed, excepting that they are not covered with boarding, conse- 

 quently there is no flitch of deal between the wrought iron bars of the 

 principals, but they are kept apart by small pieces of cast iron, and a 

 rivet passes through it and both bars; the slates are laid on iron laths 

 1 in. deep by i in., placed edgeways. Instead of the skylights over 

 the engine house being laid on the principals they are elevated 2 ft. 

 to allow for the free escape of the smoke and steam from the en- 

 gines. 



The exyerimml. — In order to prove that the accident occasioned 

 by the tailing of the roof was not in the slightest degree caused 

 by defective construction, the contractors ordered two principals 

 to be framed and boarded, and so placed that railway bars could 

 be turned from an overhanging scaffolding placed on the other side 

 of the wall near which the experimental rafters were placed ; the 

 bars were then gradually lowered so as to evenly load one of the 

 two principals until the load was equal to 40 lb. upon the square foot, 

 that being double the load intended to be carried by the roof in ques- 

 tion; the principals were then left for 24 hours fur the inspection of 

 the Inspector General of Railways (General Pasley) and other gen- 

 tlemen interested, when their ultimate strength was to be tested ; 

 which was done on the IGth of April, in the presence of General 

 Pasley, Messrs. J. and L. Cubitt, Messrs. Grissell and Peto, Mr. Ranger, 

 Mr. Fox and other gentlemen connected with the railway ; the same 

 plan of lowering the bars was adopted, and they were luaded until the 

 weight of 65 lb. per square foot broke the cast iron king head, the 

 wrought iron ratter then buckled, but did not sustain the slightest 

 fracture. Every one present expressed the greatest satisfaction at the 

 result of the experiment wliich fully carried out the statements of the 

 contractors, respecting the sufficiency of the roof. 



Enmneerikq Honours. — It is wiih great satisfaction we have to announce 

 another engineer, Dr. MacNeil, has been honoured by a knighthood, there is 

 not a member in ilie jirul'ession whois more respected than .Sir John MacNeil, 

 and we feel assured it will be a great gratificalion tolhe profession generally. 

 We have long since advocated lor honours being granted to the Engineering 

 Profession, and it. now affords us much pleasure to see that our desires are 

 being gradually fulfilled. 



15 



