1846.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



of persons in a carriage, to bring the springs into action, the position of the 

 carriage in the train, and the speed at which the train is propelled, of all 

 vrhich conditions are independent of the breadth of the gauge. We have 

 however, with a view of making our observations on this question, travelled 

 jeveral times over all those lines having their stations in London, and after 

 making, to the best of our judgment, every allowance for the circumstances 

 above-mentioned, we are of opinion that at the higher velocities the motion 

 13 usually smoother on the broad gauge. 



Merchandise.— \t is now to be considered whether either gauge has a 

 luperiority over the other in regard to the conveyance of general mer- 

 chandise. 



Under this head we class manufactured goods and their raw material, 

 mineral products, such as coal, lime, iron, and other ores ; agricultural produce, 

 inch as corn, hops, wool, cattle, and timber. 



On these points we have taken the evidence of persons well acquainted 

 with the carrying trade, and from their information, and our observation, it 

 does not appear to be of consequence to the parties sending or receiving 

 goods whether they are transmitted in wagons containing five or six tons, 

 or in wagons of larger capacity, provided that the cost and security are 

 the same, and that the carriers undertake the responsibility of any damage 

 that may result from the size of the load. But Messrs. Home and Chaplin, 

 »nd Mr. Ilayward, who are largely interested, and have had great experience 

 in the carying trade, have expressed a strong opinion that the smaller 

 wagon is far the more convenient and economical. The satpe opinion is 

 still more strongly expressed by those witnesses we have examined who 

 have experience of our mineral districts. These persons state that the 

 smaller wagon can be more easily handled, and can be taken along sharper 

 curves than would be suited to a broader wagon ; that such sharp curves 

 are very common in mineral works and districts, and that the broken nature 

 of the ground would render curves of greater radius inconvenient and 

 expensive. 



Another important difference between the two gauges, in this commercial 

 Tiew of the question, would present itself in localities in which there may be 

 a difficulty of readily obtaining full loads for the wagons at road stations. 

 Here the defect of the dead weight, which we find to apply more particu- 

 larly to the broad gauge , would be greatly increased unless another evil of 

 bUU greater commercial importance were created, that of detaining the 

 ■wagons to receive full loads. On the whole therefore, we consider the 

 narrow gauge as the more convenient for the merchandise of the 

 country. 



2. Relative Speed. 

 With a view to form our judgment on this subject, we have examined 

 the time-tables of the several companies having express and fast trains, and 

 the returns furnished by those companies of the actual speeds attained by 

 the express trains, on 30 successive days, from the 15th of June to the 15lh 

 of July, 1813. 



We have also, on various occasions, travelled in the express trains, and 

 noted the speed, mile by mile. 



The result has been, that we are fully satisfied ihat the average speed on 

 the Great M'estern, both by the express trains and by the ordinary trains, 

 exceeds the highest speed of similar trains on any of the narrow gauge 

 lines. But some of the latter have trains which exceed in speed the cor- 

 responding trains of the Bristol and Gloucester line, and also of the Swin- 

 don and Gloucester line, both of which are on the broad gauge ; but these 

 latter, it is to be remembered, are still of recent conslrnction with unfa- 

 vourable curves and gradients; and we have been informed by Mr. K. 

 Stephenson, in his evidence, that at one period the speed on the Northern 

 and Eastern line even exceeded that of the Great Western. 



In treating of a difference in the speed, other circumstances besides tlie 

 mere gauge must be considered. The inclinations and curves of the Great 

 Western Railway, between London and Bristol, and even for 40 miles be- 

 yond Bristol, are, with the exception of the Wootton-Basset and the Box 

 inclines, particularly favourable to the attainment of high velocities ; and it 

 is important to remark, that the inclinations and curves on that part of the 

 Nortliern and Eastern Railway where the competition iu speed with the 

 Great Western was the most successful are generally of a similar cha- 

 racter. 



O ne of the principle motives professed for constructing the Great West- 

 ern Railway on the broad gauge was the attaining of high speeds, and the 

 credit of the proposers and defenders of that construction has therefore been 

 deeply engaged in maintaining them. 



The elfsct of gradients on the speed of the Great Western trains, even 

 with the powerful engines used on thatline,is shown in the Time Table, page 

 24, where we find that while the speed from Paddington to Didcot by the 

 express train is 47^ miles per hour, from Didcot to Swindon it is only 41'1, 

 and from Swindon to Gloucester ouly 31'7 ; from Swindon to Bath it is 

 482, but returning only 37 2 : from Bristol to Taunton the speed is 4t}'3, 

 and from Taunton to Exeter only 39'2. 



Possibility of Future Increase of Speed. — We must observe, however, 

 that while the Great Western Company have not altered in any degree the 

 plan of their engines, the higlier velocities of the narrow gauge lines have 

 been attained by the introduction of a more powerful kind of engine than 

 was employed at an earlierperiod, and probably the new engines now used 

 on the narrow gauge are as powerful as they can well be made within the 

 limits of their gauge; whereas the broad gauge lines have still a means of 

 obtaining an increase in the puwer of their engines, and of increasing their 

 speed, providing the road be in a condition to sustain the great increased 



force which must result from any increased weight of the engine moving 

 at such high velocities. 



Whether the permanent way is in such a state at present is very question- 

 able, or even whether it bi' posiblein all vicissitudes of weather to main- 

 tain it in such a condition. We ought not to lose sight of the fact, that, 

 since the introduction of express trains the accidents arising from engines 

 running off the line have been much more common than in former years ; 

 indeed, these accidents have been more numerous within the last 

 seven months than within the preceding five years, and it is questionable 

 whether this contest for speed ought to be carried to any greater length. 

 We are, indeed, strongly inclined to the opinion stated by several engineers 

 in their evidence, that it is the stability of the road, and not the power of 

 the engine, that will prescribe the limits of safe speed. 



On the first introduction of passenger railways, speeds of about 12 miles 

 per hour only were anticipated ; the rails then employed weighed ouly 35 

 lb. per yard, and the engines about six or seven tons. As soon as speeds 

 of 20 and 24 miles per hour were attempted, it was found necessary to 

 have rails of oOlb. per yard, and engines weighing 10 and 12 tons. Since 

 that time the rails have been increased in weight progressively to G5lb., 

 75lb., and 85lb. per yard, and the weight of the engine on the broad gauge 

 exceeds 22 tons, and on the narrow gauge it now approaches 20 tons ; 

 indeed, we have seen a narrow gauge engine on six wheels weighing 3il 

 tons. We doubt, however, whether a corresponding stability has beea 

 attained in the road itself. 



Outside Cylinder Eagine». — Amongst other changes for increasing the 

 power of the engine and the speed of the trains of the narrow gauge lines 

 there have been the giving an increased length to the engine, and the placing .. 

 the cylinders on the outside of the framing ; but it is the opinion of some oC 

 the witnesses we have examined, that this position of the cylinder has a, 

 tendency to produce a greater wear and tear of the journals, and a conse- 

 quent rocking and irregular motion of the engine on the line. This, 

 however, while the engine is of medium length, has been denied by Mr.- 

 Locke, who has had great experience in the working of outside cylinder- 

 engines. But it is stated by Mr. Gray and Mr. Gooch, that where the 

 length of the engine is greatly increased, this increased length, by causing 

 the extremities of the engine to overhang very considerably the fore and. 

 hind axles, has a great tendency to increase the irregular motion producsd- 

 by the outside cylinder. 



iVIr. R. Stephenson admits that in some of the later engines this irregu- 

 larity does exist, but he attributes it to the weight of the piston and its 

 appendages, observing, " I do not believe that it is the steam that causes 

 the irregular action, but I believe it to be the mere weight of the pistons 

 themselves, and therefore if we could contrive to balance the piston by the. 

 weight upon the wheels, we should get rid of that very much." 



At all events, from whatever causes the motion may arise, the oscilla- 

 tions are very considerable in some of these long engines, and such as can 

 scarcely be considered safe at high velocities. 



This great length of engine is, however, by no means essential to the 

 attainment of high speeds on narrow gauge lines. 



We found by timing the express trains on four different journeys on the 

 South Western line, in both directions, that the whole distance was per- 

 formed very satisfactorily in about 1 hour and 52 minutes, including the 

 time of two stoppages, being at an average rate of 41 miles per hour, on 

 a line which, in one direction, rises for a length of more than 40 miles oc 

 a very prevailing gradient of 1 in 330 ; and in the other rises for several 

 miles on a gradient of 1 in 250. On each occasion a distance of five 

 miles, on a level part of the road, was passed at the rate of 53 miles per 

 hour. 



The length of the engine boiler was only eight feet seven inches, the 

 driving wheels six feet six inches in diameter; the leading wheels haa 

 both inside and outside bearings. The diameter of the cylinder in one 

 case was 15 inches, in the others 14^ inches, both outside, and attached 

 to the smoke-box, 



Evaporative Power of Broad and Narrow Gauge Engines. — In proceed- 

 ing to compare the locomotive engines, we remark, in the first place, Ihat 

 the fire-boxes, boilers, &:c., of the narrow gauge engines still possess a 

 smaller evaporating power than those of the broad gauge engines, al- 

 though recent attempts have been made to raise the former to the level of 

 the latter ; but those attempts have not succeeded ; and it is indis- 

 putable, that whatever can be done for the narrow gauge, in this respect, 

 can be surpassed on the broad gauge. And we concur in opinion with 

 many of the ablest engineers, who have stated, that the engines of both 

 gauges have nearly obtained the speed and power which it would be 

 justifiable to employ in reference to the present strength of the rails and 

 the firmness of the earthworks. 



Diameter of Driving Wheels.— We remark, in the next place, that the 

 diameter of the driving wheels of the broad gauge engines is greater than 

 than that of the driving wheels of the narrow gauge engines, and, al- 

 though, in many of the narrow gauge engines the use of the externa! 

 cylinder has enabled the manufacturers to bring the boilers nearer to the 

 driving wheel axles, and has thus permitted an increase of the diameter 

 of the wheel, still it is always in the power of the constructors of broad 

 gauge engines to make a corresponding change, and thus to mamtain the 

 superiority; for the larger diameter of the wheel is unquestionably 

 favourable to high speed, both because the steam is used to greater advan- 

 tage, and because the alternating shocks upon the machinery are less 

 rapid. It is, however, extremely difficult to say at what speeds this ad- 

 vantage becomes appreciable. We think it likely, that as far as the speed 



