304 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[July, 



After having dilated on the different modes and systems of boring, 

 the work passes to the description of the different boring apparatus 

 — as instruments for clearing and emptying, correcting apparatus, 

 instruments for boring horizontally, or for boring in the angles of 

 walls, &c. The author then details several contrivances for tubes and 

 repairing damages, and inserts a journal of a boring operation, indi- 

 cating with great accuracy the progress of the work through different 

 formations; the accidents which might have intervened, and the 

 remedies resorted to to repair and prevent them. A recapitulation 

 of the results hitherto obt lined by boring, and what may be accom- 

 plished, follows, and the author concludes this chapter by the descrip- 

 tion of some instruments which are indispensable for ascertaining the 

 extent and quality of work performed in any given time. The meaus 

 fur obviating the decrease in the flow of artesian wells, as well as 

 absorbing pits suffering under stoppages, are then given. The 

 work concludes by fixing attention on the especial laws of geology and 

 mechanics, which it is indispensable for the borer to know, and for 

 securing a proper execution of the many works in which boring is 

 now used. The plates form a very useful and interesting accessary to 

 this deserving work. 



Carpentry in Divisions of A, B, C. A Comprehensive and Useful 

 Work. By Peter Nicholson. In Twenty Parts. Part I. London : 

 Weale. 



This is the first part of a new issue of Peter Nicholson's work, with 

 additional plates, and many promised improvements. The work 

 seems likely to be what it is'styled, "comprehensive and useful;" but 

 we hope that the redundancy of Mr. Nicholson's style will be carefully 

 pruned, and that unexecuted designs (such as tlie verandah by Mr. 

 Arundale) will not be published. Mr. Nicholson's practical plates are 

 very good, but his descriptions of them are apt to run to too great a 

 length. 



Post Office Railway Directory for 1847. 



With the growth of railway kings, directors, and members of par- 

 liament, it becomes desirable to know who they are — which is, we 

 suppose, the reason for the present work, which gives an alphabetical 

 list and biography of all these functionaries. Thus we have sketches 

 of the Stephensons, Brunei, Locke, Hudson, &c., and as the book 

 ministers to public curiosity, it will in all probability be a standard. 

 We notice a list of railway engineers and mechanical engineers, with 

 the appointments they hold. 



Archilectural Maxims and Theorems. By Thomas Leverton 

 Donaldson, Professor of Architecture, University College. London : 

 Weale, 1847. 



Mr. Donaldson has published a small work, which consists of two 

 parts — a collection of maxims, and a lecture on the character of archi- 

 tects. It is a work reinark.ible enough to deter us from reviewing it 

 at the late period at v\hich we have received it. 



THE DEE BRIDGE FAILURE. 



Considerable interest has been caused among the profession through the 

 failure of a cast iron girder bridge over the River Dee, near Chester, which 

 took place on the 24th May last ; and in consequence of the accident in- 

 volving the death of some individuals, a coroner's inquest has been held, 

 which lasted several days. It not our intention to give the whole of the 

 evidence, as much of it was extraneous ; but we shall select those portions 

 which immediately apply to the construction and failure, and then offer some 

 remarks of our own, together with a wood-engraving of the girder, showing 

 the fractures, and a section. 



Mr. Thomas Alfred Yarrow, who was selected by the coroner and 

 jury to examine the bridge, said,— I have been a civil engineer for the last 12 

 years. I have held the appointment of bridge-master for Chester for some 

 time, and have no connection at present w ith any railway. I have made au 

 examination of the railway bridge over the Dee, and I now read my re- 

 port of the inspection : — 



Report, — " Upon examining the bridge, I found that the masonry and 

 ironwork, with the exception of that part of each which has fallen, were 

 in an apparently sound state. The principle of the bridge is that of 

 trussed girders of cast metal reslini; upon stone piers and abutments, 

 which are parallel to the course of the river, but askew to the railway 



above. Each girder coDsists of three pieces, having vertical flanges, with 

 bolts at the joints, and, in addition to being bolted to the full depth of the 

 girder, each joint is surmounted by a segmental piece, to receive which, 

 notches have been cast in the upper surface of the girders. The tension 

 rods descend in an oblique direction to each joint, and are carried horizon- 

 tally between them ; they consist of separate bars of wrought iron, which are 

 secured to each other laterally by clips. The portion of the bridge which 

 has fallen consists of one outside girder on the Salteney side of the river, 

 with the attached platform and transverse tension rods. Two stones, com- 

 posing part of the string course, and acting as a bed for the girder on the 

 Salieney abutment have fallen, and also the corner stone at the acute angle 

 of the opposite river pier upon which the broken girder rested. The gir- 

 der itself is broken, having two fractures in the length near to the Salteney 

 abutment, and one in its centre. Having premised this short descriptiou 

 of the construction of the bridge, and its present appearance, 1 may pro- 

 ceed to detail the facts which I have remarked during ray investigation, 

 and which have enabled me to arrive at a confident conclusion as to the 

 cause of the accident. My attention was in the first instance directed to 

 an examination of the fractured ends of the girder, for the purpose of 

 ascertaining whether any defect had existed in the castings. The appear- 

 ance of the broken surface led me to conclude that the castings had been 

 sound, and the tension bars, as far as they have yet been recovered from the 

 water, are unbroken. 



" From calculations which I have made of the strength of the girders, 

 taken from an actual measurement of the section at the point of fracture, I 

 find that, independent of any additional strength that may be obtained 

 from the tension bars, the girders alone are capable of sustaining a much 

 greater weight than could under any ordinary circumstances be placed 

 upon them. The breaking weight of each girder I calculate at 74 tons, 

 supposing the weight to be concentrated over one point, and of both gird- 

 ers 148 tons. I3ut it is an admitted principle that a beam will carry twice 

 the weight, distributed over its whole surface, that it will bear upon one 

 point. We can therefore conclude, that twice the above weight, 148-f-2 = 

 296 tons, is the breaking weight of one bay or opening of the bridge for 

 one line of rails. The weight of girders and platform is, at a rough calcu- 

 lation, about 90 tons, which must be deducted from the foregoing quantity ; 

 we have therefore 290, less 90, equal 206 tons as the breaking weight ; 

 and this is altogether without reference to the tension bars. 



" From the above facts, I concluded that the accident did not arise from 

 the breaking of llie girder as a primary cause, and I therefore directed my 

 attention to the state of the masonry and to a consideration of its sustain- 

 ing power. Having carefully examined all the displaced stone and their 

 respective beds, I found that one, previously named as forming the acute 

 angle of the river pier, and upon which one end of the broken girder 

 rested, was totally inadequate, in its form and bearing surface, to its im- 

 portant situation. This stone had sustained nearly three-quarters of that 

 portion of the Hange of the girder which rested upon the pier. The area 

 of its lower surface is 24 ft. 6 in., of which 11 ft. 6 in. only was bedded on 

 the pier, leaving 13 ft. to overhang as a cornice. The stone was not con- 

 nected by cramps or ties with the adjoining masonry of the pier. The 

 railway over the whole bridge is curved. The broken girder supporting 

 the outer side, and being subject to a greater lateral force than the girders 

 forming the inside radius of the curve, I consider that this lateral force, 

 acting during the passage of each train, must have so far loosened the 

 inefficient masonry as to cause a displacement of the girder itself and its 

 consequent fracture." 



Mr. Robert Board, superintendent of the Manaley Iron Works. — The 

 girders of the Chester railway bridge over the Dee were manufactured at 

 those works. They were tested before sent to the railway. Each girder 

 was placed side by side and tested by 50 tons of iron being put on them 

 in the centre. We took the deflection on every five tons, but have not got 

 the particulars of those deflections. The ordinary pressure on the girders 

 passing over them would not exceed 50 tons. After the girders had been 

 tested we found a flaw in one of them : it was a mere honey-cake, and it 

 was rectified before it was sent away. I have since examined the girder, 

 and found that the accident had not resulted from the flaw. The fractures 

 were in the sound metal. I superintended the fixingof the girders. There 

 are many railway bridges of tlie same kind. On the Trent Valley line 

 there are eight of the kiud. It is not opened to the public as yet, but on 

 the Blackwall railway there are several that have had heavy trains passing 

 over them for years. The one over the Dee is the largest. 1 never heard 

 of any of them giving way. Had been several times to view the bridge 

 when trains were passing over it, and found the deflection very trivial, not 

 much more tbau an inch. 



Major General Sir Charles William Pasley. — I was (he Government 

 Inspector-General of Railways when the Chester and Holyhead Railway 

 was opened. I surveyed the bridge over the river Dee on October 20lh, 

 and reported it as safe. I compared the plans witli the actual building, 

 and examined it in such detail as I deemed necessary. It is an iron girder 

 bridge, of three openings or spans of 98 feet each; wrought iron tension 

 rods are used to strengthen it. I always was of opinion, and am so still, 

 that these tension rods are not of great use, because I consider that the ex- 

 pansion of wrought and cast iron from heat diflers in some degree, although 

 not very greatly ; but that iron girders being very massive and the tension 

 bars thin and of small dimensions, the sun may act on the wrought iron 

 rods very considerably and less on the cast iron girders ; and supposing 

 them to be adjusted fur a moderate temperature, the intensity of hut wea- 

 ther may destroy their proper proportion and do away with the benefit of 



