58 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



the arguments advanced, are incorrect, and prove nothing. Another oppor- 

 tunity will probably occur of entering more fully into the real merits of the 

 question, and for that 1 shall be prepared. 



I am, gentlemen, your obedient servant, 



(Signed) I. K. BRUNEL. 

 Lumhii,Dcc, Vith, 1838. 



REPORT OF NICHOLAS WOOD, ESQ. 



TO THE DIRECTORS OF THE GREAT WESTERN RAILWAY. 



Kil/in/iworlh, Dec. 10(/i, 1838. 

 * * * • Your instructions were, that 1 should undertake an 

 examination of that portion of the Great Western Railway now completed, 

 and investigate Ihe result of the whole system wliich hM been adopted ; and 

 my attention is particularly directed to those points which may be said to con- 

 stitute the peculiar features of the Great Western line, as contrasted with those 

 of other railways, including in such inquiries the construction and efficiency 

 of the engines, as well as every matter connacted with the locomotive depart- 

 ment of the company. 



The Great Western Railway differs from the ordinary railways, in the width 

 of gauge adopted, in the construction of the rails employed in framing the 

 road, and in the adoption of much larger driving wheels than ordinary in the 

 locomotive engines. 



The subjects for consideration are therefore comprised under the following 

 heads of inquiry, viz., the width of gauge, the mode of constructing the road, 

 and the efficiency, power, &c., of the locomotive engines. 



The increased width of gauge might have been adopted, and engines of the 

 same description as those used on other railways might have been used, and 

 it does not necessarily imply that the adopting an increased width, should 

 render necessary the particular mode of construction adopted by Mr. Brunei, 

 except in one point of view in which Mr. Brunei has put it, viz. : — " That the 

 increased width of gauge was necessary for the accomplishment of a high 

 rate of speed, and that he believes continuous timber bearings to be a most 

 essential improvement where high speeds are to be obtained." Still, as the 

 two questions are in some degree distinct, we shall in the first instance con- 

 sider them separately, and shall afterwards consider them in their connexion 

 with each other, as advanced by Mr. Brunei ; and as the elucidation of these 

 two heads of inquiry, includes that of the power of the locomotive engines, 

 we shall not in this place make their consideration a'dislinct question. 



In order, therefore, to bring the subject clearly before you, I shall first of 

 all point out the objects, so far as I can learn from the published documents of 

 your body, and from the reports of Mr. Brunei, which have been expected to 

 be realized by these departures from the more general plan of constructing 

 and working railways ; I shall then state some of the most prominent objec- 

 tions which have been made against the system, after which I shall give, in 

 detail, the inquiries and experiments which appeared to me necessary, to 

 ascertain how far these benefits have been, or appear likely to be realized, and 

 to what weight the objections appear to be entitled. The result of these in- 

 quiries and experiments will be next considered, and with these materials, in 

 obedience to your instructions, the system of construction of the Great Western 

 Railway will be contrasted with the most improved railways of the ordinary 

 construction and widlh of gauge. 



Witllh ijf Gaiiije. — The width between the rails of all the public railways in 

 England is four feet eight and a half inches, the width of the Great Western 

 Railway is seven feet ; the ditTerence is therefore neariy one half more, or two 

 feet three and a half inches. From the documents previously alluded to, from 

 a careful perusal of Mr. Brunei's reports, and from personal communications 

 with that gentleman, the following appear to have been the prominent advan- 

 tages expected to be derived from the increased width of gauge, and which 

 induced the adoption of the width of seven feet. 



Attttininent of a Ak/h rale of speed On this point Mr. Brunei remarks, 



" with the capability of carrying the line upwards of tifly miles out of London! 

 on almost a dead level, and without any objectionable curves, and having 

 beyond this, and for the whole distance to Bristol, excellent gradients, it was 

 thought that unusually high speed might easily be attained; and that the very 

 large extent of passenger traffic, which such a line would certainly command, 

 would ensure a return for any advantages which could be offered to thepublic^ 

 either in increased speed or in increased accomv.iodation." For iUr. Brunei 

 remarks, " I shall not attempt to argue with those who consider any increase 

 of speed unnecessary, the public will always prefer that conveyance which is 

 the most perfect, and speed within reasonable limits is a material ingredient in 

 perfection in travelling," and the attainment of high speed appeared to involve 

 he question of the width of gauge. 



Mr. Brunei also considers, "that it would not have been embracing all the 

 benefits derivable from the favourite gradients of the Great Western Railway, 

 unless a more extended gauge was to be adopted, for if carriages and engines 

 of a certain weight have not been found inconvenient upon one railway, 

 greater weights may be employed, and the same results obtained on a railway 

 with better gradients ; and to adopt a gauge of the same number of inches on 

 the Great Western Railway, as on the Grind Junction Railway would, in fact, 

 amount practically to the use of a different gauge on a similar railway, for the 

 gaugj which is well adapted to the one is not well adapted to the other." 



Meclianicid adcanliiric of increasing Ihc Diaiiiclcrofllie Il'/iecls, without raising 

 Ihe Bodies of the Carriages. — This comprehends what is deemed by Mr. 

 Biunel, the most important part of the advantage of an enlarged width of 

 gauge, viz., the reduction of friction by the increased diameter of ihe wheels, 

 while at the same time bjr being enabled to place the body of the carriage 



within the wheels, the centre of gravity of the carriage is kept low, and 

 greater stability and steadiness of motion is expected to be attained. Four 

 feet wheels have been jnit upon the carriages at present in use upon the line, 

 but Mr. Brunei states " that he looks forward to the employment of wheels of 

 a larger diameter; and that he has been influenced to a considerable extent, in 

 recommending the increased width of gauge, by its capabilities of prospective 

 improvements, which may take place in the .system of railroads. He states, 

 " that though there , are some causes which in practice slightly influence the 

 result, yet practically the resistance from friction will be diminished exactly 

 in the same ratio that the diameter of the wheels is increased," and " consi- 

 dering that the gradient of four feet per mile only presents a resistance of less 

 than two pounds per ton, and that the friction of the carriages on ordinary 

 railways amount to eight or nine pounds per ton, being 8-lOtlis of the entire 

 resistance, any diminution of the friction operates with considerably more 

 effect upon a road with favourable, than one with more unfavourable gra- 

 dienls;" and he further says, " I am not by any means at present prepared 

 to recommend any particular size of wheels, or even any iiicrc.isc of the 

 present dimensions. I believe they will bo materially increased ; but my 

 great object would be in every possible way to render each part capable of 

 improvement, and to remove what appears an obstacle to any great progress 

 in such a very important point as the diameter of the wheels, upon which the 

 resistance which governs ihe cost of transport, and the speed that may be 

 obtained so materially depends." 



Admits all sorts of Carriages, Siagc-Coaches, Syc. to he carried icilhin the 



wheels Presuming that the adoption of wheels of a larger diameter is found 



beneficial, to the extent expected by Mr. Brunei, it became necessary that the 

 carriages to be conveyed should be placed upon platforms within the wheels, 

 to keep them as low as possible, which could not be done with carriages on 

 railways of the ordinary width, a wider gauge seemed therefore necessary for 

 this purpose. 



Increased facililies for the adoption of larger and more powerfal Locomotive 

 Engines, for the attainment of higher rate of speed. — Much stress has not been 

 laid upon this by Mr. Brunei, although it has been alleged that gre.at difficul- 

 ties exist and that considerable expense is incurred by being obliged to com- 

 press the machinery into so small a space ; and consequently, that a greater 

 width of gauge would enable the manufacturer to make a more perfect 

 machine, and by having more space for the machinery, the expense of 

 repairs would be lessened. ^ 



Increased stahilitg to the Carriages, and consequently increased steadiness of 

 motion, not from any danger to be apprehended, by the centre of gravity being 

 higher in carriages of a less width ; but that higher carriages are more liable 

 to oscillate upon the railway, than carriages of a greater widlh and less 

 heighl, and that a considerable part of the fiiction is occasioned by the 

 oscillation of the carriages throwing the flanches of the wheels against 

 the rails. 



These appear to be the more prominent advantages set forth by Mr. 

 Brunei, as consequent upon the adoption of an increased width of gauge. I 

 have taken the extracts from the report to the Bristol meeting, in preference 

 to quoting from Mr. Brunei's communications to the directors, inasmuch as 

 that report is before the shareholders ; and also in that report Mr. Brunei 

 enters somewhat minutely into details on the subject, and gives in a more 

 determined and explicit plan tlie substance of all his communications to the 

 directors on the subject. It would have increased the bulk of this report 

 unnecessarily to have given all Mr. Brunei's reasons for the adoption of the 

 increased width set forth in that document, and this is also unnecessary, as 

 the report itself is before the shareholders and can be referred to. These 

 representations and recommendations of the engineer, appear to have been 

 the principal reasons which induced the adoption of an increased width of 

 railway, as stated in your report to the shareholders, at the half-yearly meeting 

 of the 2Sth of August , 1 836. 



The objections which have been advanced against the adoption of this 

 departure from the ordinary width of lailways, have been principally the fol- 

 lowing, viz. 



21ic increased cost of forming Ihe road track of the Umlwag, in consequence 

 of a greater width of base requited for the superstructure of the rails, and 

 upper works. That the carriages were required to be larger and heavier. 

 That the increased width of gauge caused additional friction in passing 

 through the curves. That it entailed a greater expense of constructing the 

 engines and carriage, increased liability to the breakage of axles, &c. That it 

 prevented a junction of the Great Western with other railways ; and above 

 all, that there were no advantages gained, commensurate with the increased 

 expsnses and inconvenience of such a departure and disconnection from rail- 

 ways of the ordinary width, and several other objections which have been 

 urged by differenl persons against the system, which it is not necessary to 

 enumerate. 



Previously to entering upon the consideration of the presumed benefits and 

 objections incidenlal to the width of gauge, it will be advisable to bring 

 before you the second part of the system of Mr. Brunei, viz. : the mode of 

 constructing the railway, and in doing so I shall pursue the same plan as in 

 the case of the consideration of width of gauge ; first of all to point the rea- 

 sons which seem to have influenced Mr. Brunei in the recommendation of 

 this particular plan, and the improvements over other plans which he antici- 

 pated from its adoption ; I shall then briefly state some of the principal 

 objections which have been urged against it; and lastly, -detail and report to 

 you the mode I have deemed adviseable to investigate, and determine all these 

 conflicting questions, and then give the conclusions, which appear to me to 

 lesult from the enquiries and experiments 1 have made. 



Oj/iilructiuit of the Eoad.^-U will uot be necessary for nie to enter into u 



