The life of Isambard Kingdom Brunel, Civil Engineer Part 14

One of the first duties of the Commissioners was to provide for the due compliance with the order of the Board of Trade respecting the introduction of the narrow gauge, in conjunction with the broad, on the Oxford and Rugby Railway.

It was proposed to effect this either by laying a narrow gauge line concentrically between the two rails of the broad gauge, or by laying down only one additional rail between the two broad-gauge rails, making one of the latter serve for both broad and narrow gauges. Mr. Brunel recommended the second of these plans to be adopted on the Oxford and Rugby line.

After a careful consideration of the question, the Commissioners sanctioned the mixed gauge formed by the introduction of a third rail; this was accordingly laid down, and none of the dangers which were at the time prognosticated in reference to it were found to exist. It has been the plan almost exclusively used in the many cases where the combination of the two gauges has been required.

In 1846 the Great Western Railway Company had promoted a bill for a branch to Birmingham from the Oxford and Rugby line at Fenny Compton.

The Act was obtained, but they were defeated on the question of the gauge. However, after the pa.s.sing of the Gauge Act, the Company again attempted to carry the broad gauge to Birmingham. Their application was backed by a strong memorial from the districts interested, and in June 1847 an order was pa.s.sed by the House of Lords directing the Board of Commissioners of Railways--

To inquire into the accommodation afforded by the several lines of railway now open, or in the course of construction, or projected, between London and Birmingham; and to report to this House, early in the ensuing Session of Parliament in what manner they are of opinion that the interests of the public may be most effectually ecured in regard to such lines; and whether it is expedient that the broad gauge should be extended to Birmingham; and if so, in what manner such an arrangement can be carried into effect with the least interference with existing interests....

This, of course, opened up again the whole question of the comparative merits of the two gauges.

The Railway Commissioners issued a series of queries addressed to the officials of the Great Western and the London and North Western Railway Companies, and others. On the part of the Great Western, answers were given by Mr. Brunel and Mr. Daniel Gooch. Mr. Gooch also furnished the results, with tables and diagrams, of a very comprehensive series of dynamometrical experiments, made by him on a mile of straight and level line on the Bristol and Exeter Railway. These experiments fully demonstrated the advantages of the broad gauge, and are still the chief authority on train resistances.[58]

In their report the Commissioners adopted the opinion of the Gauge Commissioners 'that a break of gauge was a most serious impediment in the transport of merchandise, and that the broad gauge did not offer any compensating advantage so far as that description of traffic was concerned.' In regard, however, to pa.s.senger traffic, they found a case for further enquiry. They said--

It is notorious that higher speeds, with larger and heavier pa.s.senger trains, are regularly maintained on a part of the line of the Great Western Railway than on any other railway in the country.

This fact is known and greatly appreciated by a very large portion of the public; and no opinion respecting the extension of the district within which the broad gauge should be adopted is likely to be received with confidence which is not founded on a full consideration of the circ.u.mstances to which the above fact is to be attributed, and of the extent to which, under differing circ.u.mstances, if attributable to the breadth of gauge, the gauge of the Great Western Railway offers this advantage (p. 11).

They a.s.sumed that the greater speed was due to greater engine power, and they admitted that the increase of gauge allowed of an increase in the size and power of the locomotive. They arrived at the result that the broad-gauge engine 'can draw on a level an ordinary 'pa.s.senger train of 60 tons with as much facility at 'sixty miles an hour as the narrow-gauge engines can at 'fifty,' the advantage, however, diminis.h.i.+ng with steep gradients. In their report the following pa.s.sages are to be found:--

Such appear to the Commissioners to be the advantages which the broad gauge at present offers; and although they cannot consider them sufficient to compensate the evils attendant on two gauges, if it were now possible to obtain uniformity of gauge, yet, as two gauges are established, it appears to them that it might be expedient, and for the public interest, on account of those advantages, to extend the broad gauge to Birmingham ... (p. 14.)

By introducing the mixed gauge on the Birmingham and Oxford Junction Railway, the line from Birmingham by Fenny Compton to London would probably offer, as a broad-gauge railway, as rapid a communication as the existing direct line;[59] and great as the advantages which the public have received by the rivalry between the gauges, in the rapid improvement in railway travelling, have been, it might even be expected that these would be further increased when the two systems are brought into direct compet.i.tion, which as yet they have not been (p. 16).

The report of the Railway Commissioners was presented in May 1848. Their decision was ratified by the pa.s.sing of an Act in the same session for extending the broad gauge from Oxford to Birmingham; and the line was opened in October 1852.

Beyond Birmingham the Great Western Company purchased existing railways leading through Wolverhampton and Shrewsbury to Chester, and obtained access to Birkenhead and Manchester. It thus secured a communication with the great Lancas.h.i.+re towns and the manufacturing districts.

But all the lines north of Wolverhampton had been constructed on the narrow gauge, and therefore, unless the broad gauge had been laid down on these lines, there was a break of gauge between the northern districts and London.

The break of gauge was found to be a much more serious evil than had been antic.i.p.ated by the Great Western Company when they were fighting their great battle in 1845. For pa.s.sengers the inconvenience was unimportant; but for the goods traffic between the manufacturing towns and London it was serious, partly on account of the expense, but more especially in consequence of the loss of time. The delay of some hours by change of waggons, where great compet.i.tion existed, was fatal.

For these reasons the abolition of the break of gauge became desirable.

The number of narrow-gauge lines had by the year 1861 been so increased that there was no longer any hope of advantageously extending the broad gauge in the north. Therefore the mixed gauge was completed to London.

After the establishment of the narrow-gauge communication on the northern lines of the Great Western, and its prolongation to London, there was but little inducement to use the broad gauge north of Didcot.

So far as it extended, the broad gauge had exhibited in a marked degree the advantages Mr. Brunel claimed for it, and which were neither few nor unimportant.

It may be desirable before concluding this chapter to sum up those advantages:--

1. It gave the power of constructing more powerful engines, by which greater speed for pa.s.senger trains and greater tractive power for heavy goods trains were obtained.[60]

2. It gave more s.p.a.ce for the convenient arrangement and beneficial proportions of the machinery, as well as for convenient access to it. In all these points difficulties had been found on the narrow gauge; and the compulsory restriction of so important a dimension as the width between the rails has been a bar to any improvements of great magnitude or comprehensive nature.

3. It gave, even with the overhanging carriage, the facility for obtaining large wheels, and consequently diminis.h.i.+ng the axle friction without sacrifice of stability.

4. The greater width of base for the carriages to rest on gave increased steadiness and smoothness of motion, particularly at high speeds. It was the impulse given by the increase of speed and comfort obtained without difficulty on the broad gauge, which had led to the chief improvements introduced in railway travelling.

5. Greater safety was secured, particularly at high speed, from the greater stability of position due to the wider base, producing increased steadiness and diminis.h.i.+ng the chance under exceptional circ.u.mstances of the derangement of any part of the train.

6. While the broad gauge was but little more costly than the narrow, the width of the works being determined not by the width of the rails, but by the width of the carriages, and the extra cost of rolling stock being very small,[61] the broad gauge could be worked more economically under parallel circ.u.mstances than the narrow.

7. It gave the facility of using broader vehicles with equal steadiness, in cases where the extra breadth would be useful, though the extra breadth was by no means an essential part of the scheme.

The truth of these a.s.sertions, as establis.h.i.+ng the superiority of the broad gauge, was of course vehemently denied by the advocates of the narrow gauge.

One objection urged by them, the inconveniences of the break of gauge, has undoubtedly been proved by experience to be a very powerful one, so powerful indeed as to compel the abandonment of the broad gauge on the lines where any considerable quant.i.ty of goods traffic has to be carried in compet.i.tion with other companies.

Had Mr. Brunel's original plan been carried out, and had the broad-gauge companies taken possession of all the western portions of England, and avoided extensions into the north, the points of contact would no doubt have been so unimportant that no great inconvenience would have arisen, or a few miles of double gauge would have removed any difficulty; but, under the actual circ.u.mstances of the case, the Great Western Company were forced to yield.

The advantages of the broad gauge were so much appreciated by the districts it served, that its abandonment was viewed with considerable displeasure, particularly in the neighbourhood of Birmingham; but the inconvenience of double traffic arrangements far outweighed the advantages derivable from the use of the broad gauge, to the limited extent it could be applied on those outlying portions of the Great Western system. For these reasons the Company came to the determination to work their northern lines on the narrow gauge only.

The broad gauge is therefore now confined to the district for which it was originally intended. Even in this district there are many points of contact with the narrow gauge; but the inconveniences of break of gauge are by no means so important as they were in the north, and do not, at present at least, menace the continued existence of Mr. Brunel's design.

CHAPTER VI.

_THE ATMOSPHERIC SYSTEM._

A.D. 1840--1848. aeTATIS 35--43.

PRELIMINARY OBSERVATIONS--THE SOUTH DEVON RAILWAY--DESCRIPTION OF THE ATMOSPHERIC SYSTEM--HISTORY OF ITS INTRODUCTION PRIOR TO 1844--REPORT BY MR. BRUNEL, RECOMMENDING ITS ADOPTION ON THE SOUTH DEVON RAILWAY (AUGUST 19, 1844)--EXAMINATION OF THIS REPORT--MR.

BRUNEL'S EVIDENCE BEFORE THE SELECT COMMITTEE ON ATMOSPHERIC RAILWAYS, 1845--HISTORY OF THE APPLICATION OF THE SYSTEM ON THE SOUTH DEVON RAILWAY, 1844-1848--REPORT ON STATE OF WORKS (AUGUST 28, 1847)--REPORT ON CAUSES OF FAILURE (AUGUST 19, 1848)--ABANDONMENT OF THE SYSTEM, SEPTEMBER 1848--_NOTE_--COMPARISON OF STATIONARY AND LOCOMOTIVE POWER.

In the year 1844 Mr. Brunel recommended the adoption of the Atmospheric System of propulsion on the South Devon Railway, a line of 52 miles in length, which he was then constructing between Exeter and Plymouth. This system had, under the management of Messrs. Clegg and Samuda, been in operation with success on the Dalkey line for some time before Mr.

Brunel adopted their apparatus on the South Devon Railway. After it had been in use on the South Devon for about twelve months, it was abandoned, and the railway worked throughout by locomotives.

It is therefore as important as it is interesting to examine the causes of the failure of the Atmospheric System, and to consider the reasons which induced Mr. Brunel in the first instance to adopt it, and afterwards to recommend its abandonment.

Up to about the year 1843, the cost of railways, which was in a great measure due to the conditions imposed by the limited capabilities of the locomotive, had prevented their construction, except in cases where they would secure a large traffic, and at the same time traverse what was then considered a practicable country.