252 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[August, 



of the House of Commons on the Chester and Holyhead Railway 

 (No. 1), we fxive verbatim the following extracts, which will pro- 

 bably be deemed conclusive : — 



" I'erliaps I may at once explain to the Committee the idea I have adopted. 

 I conceive a iul>e — supposing a wrought-iron tube — to extend across the 

 straits ; that that ttihe to have, we will say to have 25 feet diameter, to hold 

 a line of railway, and the line of railway would run inside of it. In addi- 

 tion to that, we should have to erect a chain platform for the purpose of the 

 building. Then the question would arise, whether the chains would be al- 

 lowed to remain, or whether they would be tatten down. My own opinion is, 

 that a tube of wrouyht-iron would possess diffident strength to support a 

 railway. I am instituting a series of experiments with Mr. Fairbairn, of 

 Manchester. In fact, he is already in possession of experiments with respect 

 to iron ships which place the thing beyond a doubt, lie has ascertained that 

 a vessel of 250 feet in length, supported at the ends, will not yield with all 

 the machinery in the middle." 



Here it appears that l\Ir. Stephenson not only thought, in May 

 IS 15, that the tube might be made sufficiently strong of itself, hut 

 that the experiments of yiv. Fairbairn removed all doubts on the 

 subject. Further on, the Minutes of Evidence are as follows : — 



" It occurred to me that a rigid platform might be obtained by substituting 

 a tube in addition to the chains. Then, on going into the calculation of the 

 strength of the tube, I found that I did not require the chains themselves." 



In anotlier place, the following questions and answers occur : — 



" Q. You have not made up your miud as to the safety of dispensing with 

 the chains ? 



yi. No, I have not. 



Q. It would he impossible to do so until it is constructed, would it not ? 



A. I would rather leave that, because I would make the design so that the 

 chains might either be taken away or left ; and during the construction we 

 should have ample opportunity of ascertaining whether we could safely take 

 away the chains or not. 



Q. There would be no great advantage from taking away the chains? 



A. No; only it would make it more costly if they remained : they would 

 be applicable to other purposes, and they would cost from thirty to forty 

 thousand pounds." 



The opinion of Mr. Stephenson as to the expediency of remov- 

 ing the chains, is not expressed here quite so strongly as before, — 

 but distinctly enough to show that Mr. Fairbairn is mistalten in 

 supposing that Mr. Stephenson insisted, for several months after 

 March 18+5, on the application of chains. We readily believe that 

 Mr. Fairbairn has correctly stated the impression on his own miud; 

 and the apparent contradiction may be easily reconciled by sup- 

 posing that the subsequent experiments, and perhaps the opinions 

 expressed by Mr. Hodgkiuson and others, shook that faith in the 

 strength of the tube alone which Mr. Stephenson had when before 

 the Committee on the Chestfr and Holyhead Railway. 



In the Report presented by him to the directors of that railway, 

 twelvemonths afterwards — (February 9, 184G) — lie treats the ques- 

 tion of the adoption of chains as still undecided: — 



** The application of chains as an auxiliary has occupied much of my at- 

 tention ; and I am satisfied that the ordinary mode of applying them to 

 suspension bridges is wholly inadmissible in the present instance; if, there- 

 fore, it he hereafter found necessary or desirable to employ them in conjunc- 

 tion with the tube, another mode of applying them must be devised, as it is 

 absolutely essential to attach them in such a manner as to preclude the pos- 

 sibility of oscillation." 



Throughout this paragraph Air. Stephenson expresses a doubt as 

 t'^ the expediency of using chains. It seems, therefore, a neces- 

 sary inference that his final determination to abandon those ad- 

 juncts must have been produced by subsequent information : and 

 we cannot see how Mr. Fairbairn could prove that the information 

 was derived from his experiments exclusively, and not from a 

 general review of all the experiments undertaken. We find, in- 

 deed, the following statement by him in a foot-note (p. 22) : — 



" The drawings and designs for the Britannia and Conway Bridges were 

 made out, and the parts proportioned, without the aid of Mr. Hodgkinson's 

 formula; ; and the ab )ve, as well as other hollow girder bridges, have since 

 been constructed independently of that gentleman's assistance." 



Rut surely so general a statement must be extremely injudicious, 

 unless supported by very distinct and specific proofs. As far, how- 

 ever, as we can perceive, there is not even an attempt to give evi- 

 dence of the alleged construction of the Britannia and other hollow 

 girder bridges independently of Mr. Hodgkinson's assistance. On 

 the contrary, a few pages furtlier on, we find Mr. Fairbairn stating 

 in his report to the directors of the Chester aud Holyhead Rail- 

 uay — 



•' In the pursuit of the experiments on the rectangular, as wrll as other 

 description of tubes, I have been most ably assisted by my excellent friend, 

 Mr. llodgkinson ; his scientific and mathematical attainments render him 

 well qualified for such researches : and I feel myself indebted to him for the 



I X 



kind advice and valuable assistance which he has rendered in these and other 

 investigations." 



— How does Mr. Fairbairn reconcile this last statement with the 

 previous assertion ? 



With respect to the cellular structure of the top and bottom of 

 the tube, Mr. Fairbairn certainly a]>pears to have established his 

 claim more fully. This point is a very important one. It is un- 

 deniable that the peculiar, and altogether novel, form adopted for 

 these parts of the bridge, constitutes one of its most essential 

 features. The first notice or suggestion of this cellular structure 

 appears in a "private"* letter from Mr. Fairbairn to Mr. Stephen- 

 S(ui, dated Millwall, Sept. 20, 184'5. After noticing some experi- 

 ments on elliptical and other tubes, the letter proceeds : — 



" The defective powers of resistance of all the tubes of this shape, have 



suggested a new arrangement and distri- 

 bution of the metals ; it being evident 

 from the experiments that the tube viM 

 resolve itself into a huge hollow beam 

 or girder, leaving the two resisting forces 

 of compression and extension as wide 

 apart as possible. It is further conclu- 

 sive, that the sides must be made com- 

 paratively light, and considerable addi. 

 tional material introduced into the top 

 and bottom of the tulie. This will give 

 greatly-increased strength ; and a few 

 more experiments will determine which 

 of the two shall have the preponder- 

 ance. It is more than probable that 

 the bridge, in its full size, may take 

 something of the following sectional 

 shape." 



Mr. Fairbairn calls the atten- 

 tion of his readers to the close 

 resemblance of the sectional form 

 indicated in the sketch to that 

 of the bridges actually constructed 

 for the Convi'ay and Menai Straits; and certainly lie'is fully justi- 

 fied in insisting on the very close similarity. The only ambiguity 

 of the above quotation is the phrase "The defective powersj &c., 

 have suggested a new arrangement." To whom did that suggestion 

 occur? — Is the writer to lie understood as expressing his own 

 ideas only, or the collective deliberations of the several persons 

 present at the experiments described.'' 



The remaining question as to the invention of the methods of 

 raising the tube and some other points, we must leave for a subse- 

 quent paper. We cannot, however, conclude, without repeating 

 the expression of great regret at the circumstance, that the two 

 principal experimenters, Mr. Hodgkinson and Mr. Fairbairn, per- 

 formed their experiments independently of each other, and main- 

 tained strict reserve as to the results. How far better might it 

 have been for science, could they have worked together as hereto- 

 fore ! May we not hope that the day may come in which we may 

 again receive instruction from the associated labours of men who 

 have already worked together so well for the public benefit.'' Our 

 respect for Mr. Fairbairn must not induce us to conceal the 

 opinion that be has taken a very ill-advised step in attempting to 

 exalt himself at the expense of his colleagues. Had he contented 

 himself with a simple statement of his share of the transaction — 

 what experiments he made — what suggestions he offered — -wliat 

 labours of every kind, theoretical or practical, he undertook in aid 

 of the great result, — no blame could have attached to him. M'e 

 willingly allow that his labours were great and deserve great 

 praise — nay, we will confess that the perusal of the present work 

 has increased our admiration of his efforts considered by them- 

 selves. But surely others worked well and ably too. Ilehiniself 

 gives reiterated proof of the anxiety and toil which this under- 

 taking cost Rlr. Stejihenson. And we know that the investigations 

 of Mr. Hodgkinson were most laborimis, and confidently believe, 

 that wlien published, they will be esteemed among his most suc- 

 cessful researches. 



We cannot tell with whom the system of distrust and jealousy 

 began; but to these feelings are to be attributed all the unfor- 

 tunate results that followed. Let us hope that these feelings will 

 be soon consigned to oblivion by a generous acknowledgement of 

 mutual mistakes, and be rephiced by a worthy emulation of "in 

 honour preferring one another." 



A short time will probably suffice to put the public in possession 

 of further and independent information respecting the history of 



* Mr. Fairb'iirii dues not a]>pear to st.ite anywhere that the ^'U 'plication of private let- 

 ters adjiesceti to him was auliiorisetl by the writer. 



