THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



average power of engine which will be the same in cither case, tlie former, — 

 namely, 34 per cent, of increased effect — would be the correct mode of consi- 

 dering the comparison. I will assume, however, the latter, as being least 

 advantageous, and I will suppose the engines, although different in power, to 

 be of the same weight. Now, the resistance in ascending and descending a 

 plane of 4 feet per mile will be 100 and 66 ; with the 10 feet per mile, it will 

 be 120 in ascending, and actually only .19 in descending. 



In the case of the Great Western Ilailvvay, from London to Slough, Maiden- 

 head, Reading, and to the point of departure to O.xford, the maximum rise is 

 4 feet. Had it been 10 feet, as I must infer would have been the recom- 

 mendation of Mr. Hawkshaw, the resistance going and coming would have 

 been 126 and 39. Now, of what avail would it have been, that in returning to 

 town the resistance was small? No more passengers or carriages couli be 

 brought one way than must be conveyed the other, or, to apply one of Mr. 

 Hawkshaw's own similes, the eight horses required to take the poft-chaise out 

 must return with it, though two might be enough. I quite agree with the 

 opinion very strongly expressed in another part of the report, that for the 

 economical working of locomotive engines, their power should he irc/l propor- 

 tioned to the load they have to draw. It is remarked, apparently in allusion 

 to one which we consider the best engine in our establishment, that to use an 

 engine capable of drawing 200 tons, to drag loads averaging TiO tons, will be 

 very like fastening eight horses to a post chaise. Although the remark s.ivours 

 of ridicule, I quite concur in it. It is a forcible description of the practical 

 working of a line with gradients of 10 feet per mile, such a line as the ima- 

 ginary one ( A B) described in p. 49 of the report. 



Now, on this line (A B), the engines going in one direction would have to 

 exert a power of 126, and this at full speed, and in the other of 39, or as 200 

 to 62 — a proportion not very different from the 200 to 50, which is mentioned 

 only as something that would be very absurd. 



Again, at another part of the report (p. 53), it is stated, that engines of little 

 more than two-lhirds the power of those on the Grand Junction Railway, and 

 therefore of conskleriibhi Ifss weight, would be sufficient on our line fnmt our 

 Hatter gradients. Such an admitted reduction of '25 per cent, in locomotive 

 power seems to me no mean economy to be obtained by these gradients, the 

 effects of which are treated so lightly at other times; but these contradictory 

 results are the necessary consequences of an attempt to argue against the 

 simple facts, that the inclination of the line increases the resistance, and that if 

 a regular speed is to be maintained, you must have power in proportion to that 

 resistance. 



All the foregoing calculations upon gradients have been limited to the two 

 cases of 10 feet and 4 feet per mile. These are both unusually favourable, and 

 their comparison therefore is not calculated to render the advantages so striking ; 

 but had the gradient of4 feet per mile been compared with themoreordinary ones 

 of 10 foot and 20 feet, the superiority would have told much more in the dis- 

 cussion of the general question of the value of good gradients. To supply this 

 deficiency, I subjoin a table of the comparative effects of the same engine, with 

 the same consumption of fuel, and travelling at the same speed on the level, 

 and on the four gradients of 4, 10, 10, and 20 feet per mile, with a resistance 

 of 81bs. for friction, &c. ; and for the sake of uniformity with the previous 

 calculations, I take the same standard of 100 as the useful effect, or nctt load, 

 up the plane of ten feet: — 



Comparative Effective Power. 

 Ascending. Descending. 



Level .... 170 . 170 



4 feet per mile . . . 134 . 226 



10 feet per mile , . . 100 . 400 



16 feet per uiile ... 77 , 1;}U.5 



20 feet per mile . . . (JO ; the load onec in 



motion >\oiiKl 

 ruit of itself. 

 The discrepancy between these results and those given in the report does not 

 arise merely from different data being assumed, and upon which there might be 

 a difference of opinion ; but from errors in the treatment of the calculation of 

 the latter. I subjoin a similar table, calculated upon the basis of 101b. per ton, 

 being the total resistance on a level : — 



Comp.arutive Effective rower. 

 Gradients. .Ascending. Descending. 



Level .... )o6 . 1.50 



4 feet per niiln . . . 120 . 1 (1.3 



10 feet per mile . . . lUO . 207 



16 feet per mile ... SO . .5.J6 



20 feet per mile , . . (JO . 720 



By these tables the great superiority of a line approaching to the level is 

 made apparent , not only is the effective power of the engine in that direction 

 of the line which limits the load much greater, but the average work of the 

 engine is performed more economically by the greater regularity of the 

 resistance. On an inclination of ten feet per mile, as I have before shown, the 

 ensine, during half the time, is b.ircly perfomiing m quarter of the work of 

 which it is capable. On gradients of 10 feet per mile, the engine during half 

 the time is barely doing more than driving itself. 



These are incontrovertible facts ; whether the total resistance arises from 

 friction, from the resistance of the atmosphere, or from whatever cause, the 

 amount is about as stated, and the increase caused by the gradients is in the 

 ratio stated in the above table. 



It appears to me aln\ost to weaken the strength and obscure the clearness of 

 a demonstration which is mathematical in its correctness and certainty, to 

 attempt to support it by reference to certain experiments in which other causes 

 might have operated ; but on the Great Western Railway wc have every day, 



»nd with every train, such evident smd striking proofs uf the effect of gradients, 



that I should have thought it must be conclusive to any one who has had an 

 opportunity of witnessing them. 



With powerful engines and light trains, running at a good speed of 30 to 

 35 miles per hour, the changes of gradients, (which only vary from a level to 

 2 feet per mile, and to 4 feet per mile,) are perfectly perceptible in the in- 

 creased or diminished speed, even without the assistance of a watch, and have 

 been frequently detected by persons previously unacquainted with the levels. 



It must always be borne in mind that the resistance arising from the gra- 

 dients is a permanent evil which, once established by the completion of the 

 works, cannot be remedied, and the probable future effects of this must there- 

 fore be serioitsly considered. In the course of a few years, as railway travel- 

 ling becomes general throughout the country, and there are opportmiities of 

 reaching different parts of England by different roads, the usual results of 

 competition will follow ; prices will gradually be lowered ; the number of tra- 

 vellers will become immensely increased ; and the gross profits and expenditure 

 become proportionably large ; bearing then, particularly the latter, a much 

 greater ratio to the original outlay than at present. The profits will then 

 depend mainly upon the economy of transport, and then any saving in the 

 current expcns. s will be felt in a far greater degree. 



I shall now consider the subject of the width of gauge. The question of the 

 disadvantage of differing in point of gauge from other railways, and the con- 

 sequent exclusion from communication with them, is the first. This is un- 

 doubtedly an inconvenience ; it amounts to a prohibition to almost any rail- 

 way running northwards from London, as they must all more or less depend 

 for their supply upon other lines or districts where railways already exist, and 

 with which they must hope to be connected. In such cases there is no 

 alternative. 



The Great Western Railway, however, broke ground in an entirely new dis- 

 trict, in which railways were unknown. At present it commands this district, 

 and ha? already sent forth branches which embrace neatly all that can belong 

 to it ; and it will be the fault of the company if it does not effectually and 

 permanently secure to itself the whole trade of this portion of England with 

 that of South Wales and the south of Ireland ; not by a forced monopoly, 

 which could never long resist the wants of the public, but by such attention to 

 these wants as shall render any competition unneccessary and hopeless. Such is 

 the position of the Great Western Railway. It could have no connexion with 

 f.ny other of the main lines, and the principal branches likely to be made were 

 well considered, and almost formed part of the original plan ; nor can these 

 be dependent upon any other existing lines for the traffic which they will 

 bring to the main trunk. 



At the London extremity, from the moment the junction, as originally pro- 

 posed, with the London and Birmingham Railway was obliged to be given up, 

 there existed no possibility of a connexion with any other line. London will 

 always be the terminus of those main lines now established, and which ap- 

 proach it from distinct quarters, and the traffic of each will cease at this 

 point ; and, unless when two such lines unite to form a common entrance into 

 the town, they will have no connexion with each other at this extremity. 



The Great Western was therefore free to adopt its own dimensions ; arid none 

 of the difficulties which would entirely prevent such a course in the north of 

 England had any existence in the west ; and consequently, all the general 

 arguments advanced, and the comparisons made, on the supposition of such 

 difficulties occurring — all excellent in case they did — are totally inapplicable 

 to the particular case of the Great Western Railway, to which they have no 

 reference whatever. 



The reasons for adopting any increased width'of gauge, and the particular 

 dimension of 7 feet, have been so frequently before you, that it is unnecessary 

 for me now to repeat them. The principal positive objection urged against it 

 in the Report is the increased cost, while the mechanical advantages arc 

 doubted, but not disproved. 



As regards the cost, I have repeatedly shown that this amounts at the 

 utmost to a slight increase in the quantity of earthwork, and that the bridges, 

 tuimels, &c., are not necessarily affected. Mr. Hawkshaw seems to be of the 

 same opinion, as at p. SO he classes the " tunnels of 30 feet diameter" among 

 " the non-essentials," as " not absolutely consequent on the increase of gauge ;" 

 and at p. 50 he clearly limits the increased expense of construction to the 

 earthwork, land, and permanent ivay. There is some inconsistency in these 

 remarks, when compared with the estimate in page 52, where the width of 

 tunnels is considered a consequence of the wide gauge, and a saving of 

 estimated of 20 per cent. " in the tunnelling yet to be done, by the narrower 

 gauge requiring 4 feet less width." 



I have only here to repeat, what is really capable of the clearest proof — viz., 

 that the greater width of tunnels, proposed by me for special reasons, which 1 

 have explained on more than one occasion, has nothing whatever to do with the 

 wide gauge, inasmuch as tunnels of the ordinary width could be adopted, and 

 the saving pointed out would not, therefore, be necessarily the result of the 

 return to a narrower gauge. But the arguments advanced at p. 50 in the 

 Report, to show the necessity of increasing the earthwork by 4 feet, are 

 subsequently, without observation, applied to the tunnels. This error is occa- 

 sioned by neglecting to give precise dimensions to quantities quite capable 

 of it. 



Arguments are founded upon the assumption that a certain width is necessary 

 between the centre rails, for repairs. This is true ; but the width should be 

 stated in feet and inches. On the Liverpool and Manchester, this space is 

 4 feet 8 inches ; and even with stone blocks, this is found ample for all the 

 purposes of repair ; indeed, it is the width which is so perfect in Mr. llawk- 

 shaw's estimation. Four feet 8 inches, with stone blocks ( ivhicli does not leave 

 more than 2 feet 8 inches between the blocks,) are not equal to 4 feet with 

 longitudinal wooden sleepers, vrhich would leave fiom - feet » inehes to 3 feet 



