HIG.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



53 



So that if we leave mere generalities and come to actual calculation, the 

 whole theory seems fallacious enough. M'hat is the pressure in the case 

 in question compared with that which the carriages aad engines exert ou 

 each other when the engine has to be reversed to move carriages back- 

 ward? And this occurs daily and hourly without any rery disastrous con- 

 sequences. 



A much more serious source of accidents on the Norfolk Railway ap- 

 pears to us to be the manner in which the tranverse sleepers are laid. 

 Being made from unsquared timber sawn in half lengthways, their form is 

 hemi-cjlindrical. Now these half cylinders are not (we understand) laid 

 with tlieir flat sides downwards, as in many other railways where they are 

 of course (irmly supported by the soil : but in the Norfolk Uailway the 

 sleepers are laid with the flat sides uppermost. The hold which the 

 rounded sides have on the soil is comparatively small, and it is obvious 

 that a pressure on one side of the upper side of the sleeper might easily 

 cause it to slip round. If for instance, a stone resting on the edge of the 

 sleeper were pressed upon it by the passing of the train, it would certainly 

 tend to shift the position of the sleeper, and therefore of the rails. 



Mr. Robert Stephenson's Report. 



The following report upon tlie causes of this deplorable occurrence has 

 been presented by Blr. Robert Steplienson to the directors : — 

 To the Directors of the A'oi/o/A; Railway. 



Gentlemen, — Absence from London on urgent business has prevented 

 me complyiiis earlier with your request that I should report to you my ob- 

 servations on the statements made in tiie evidence given at the inquest on 

 the late (.ccident upon the Norfolk Railway. 



I returned to town last night, and now proceed to lay before you such 

 remarks as have suggested themselves. In the outset 1 may state, thai 1 

 concur generally with the engineering evidence given by Mr. Bidder and 

 Mr. Marshall. I shall therefore contine my observations to the evidence of 

 General Pasley, but before I direct your attention to the individual siate- 

 roeuts, I must observe, that I have experienced considerable difficulty in 

 dealing with them, in consequence of their being merely expressions of 

 opinion, without adducing arguments or specific facts to support them. If 

 the General had, after giving an opinion, stated the particular reasons or 

 result of calculations which led him lo such conclusions, then their validity 

 mioht have been tested. In the present instance such a course is duulily 

 necessary, because the subject, from the tone assumed, is made not merely 

 a scientific one, but one involving professional character. I shall, however, 

 confine my remarks to the former. 



General I'asley commences by stating that the description of engine 

 was one of "extraordinary length, of such a length as was never used ou 

 the narrow or any other gauge." 



From this statement everybody would conclude that this class of engine 

 was not in very general use ', that little or no experience bad been obtained 

 of its peculiarities ; that it was an experimental engine, possessing several 

 obvious defects. 



Against this assumption 1 only think it necessary to state the fact that 

 upwards of 150 engines of this description have been in daily use in this 

 country and ou ihe continent for the last two or three years ; that the long 

 boiler has, by evei'y experienced and impartial locomotive manager with 

 whom I have communicated, been received as a decided improvement; so 

 much so, that since this class of engine was first introduced, the boilers of 

 old engines have been, in several cases within my own knowledge, very 

 considerably lengthened ; thus ofl'ering the most incontestable proof that 

 the old construction of engine is admitted lo be deficient in length of boiler. 

 You will bear in mind that I am now speaking of the boiler simpl\ ; tiie 

 olher parts of the construction of the engine upon which General Pasley 

 oilers an opioiou I shall come lo afterwards. I need hardly say, that dur- 

 in'Tthe working of such a number of engines over such a length of time, it 

 is impossible to conceive the avoidance of accident, if this construction of 

 engine involved danger to the extent stated by General Pasley : but, us if 

 to meet this argument, the (ieneral in his evidence qualifies his opinion of 

 danger by saying, "that such an engine as the one in question Ciin go at 

 SO or 35 miles an hour, and I think 1 have gone 4:') miles upon them." 



I can only state my own experience leads me to a different conclusion, 

 and that I have frequently been upon this description of engine when the 

 speed far exceeded those above referred to without the slightest accident 

 occurring. 



Oscillation in the body of the engine at high velocities I regard as in- 

 evitable, no matter what the construction may be ; but this oscillation 

 arises from causes which cannot have come within Ihe Inspector-General's 

 sphere of observation. It is only the practical man whose opinion on such 

 points can be depended upon ; it is not the occasional riding upon an en- 

 gine that can enable any one lo decide between the construction of one 

 class and another, or to decide that dangerous oscillation is caused by an 

 overhanging firebox or a long boiler. In a word, to decide a point of this 

 kind it is absolutely essential to examine the condition ef the engine as 

 well as its construction ; for instance, the steadiness of all six-wheeled en- 

 gines essentially depends upon three conditions, — 



1. The distribution of the weight upon the three axles. 



2. The lateral play in the bearings. 



3. The distance betw. en the extreme axles, that is, the extreme length 

 of bearing upon the rails. 



Of these the last only is permanent ; the two first are constantly subject 

 to change. An engine which is perfectly safe and comparatively steady 

 to-day may become unsuady, and even dangerous at high speeds, in a 

 short time by an alteration either in tlie springs or by the lateral wearing 

 of the bearings. Now, I have reason to know that Ihe While Horse 

 of Kent, the only engine which General Pasley quotes as having oscillated 

 excessively, allhongh he has tried several others, was not in tiie best work- 

 ing condition at the time he made the experiment ; no opinion wiih refe- 

 rence to its motion could therefore with propriety be drawn without taking 

 into account the condition in which Ihe bearings were at the time, together 

 with the disposition of weight upon the wheels. 



All eugines when allowed to get play upon the bearings become un- 

 steady at high velocities, and oscillation from this source is aggravated if 

 more than a due proportion of weight be thrown upon the middle pair of 

 wheels. 



I believe nearly all the accidents which have occurred by eugines leaving 

 the rails are mainly attributable lo want of attention to this condition. 



In bad weather, when the rails are slippery, the temptation to the en- 

 gineman to increase the weight upon the driving wheels is very great, and 

 I have frequently known it carried to an improper extent. How far this 

 may have operated in the Norfolk Railway accident cannot now be ascer- 

 tained, but, referring to that which took place during the progress of Ihe 

 experiments on the Great North of England Railway, under the Gauge 

 Commission, 1 have ascertained that this improper distribution of weiaht 

 was one of the cliief causes of the engine leaving the rails. Ou a piece of 

 absolutely perfect road this cause would in all probability not have pro- 

 duced the result, but in cases of this kind the ultimate result seldom, very 

 seldom indeed, flows from one cause ; it is the concurrence of two or more 

 circunl^tances operating in the same direction. 



If accidents on railways arose from any pecularities of construction in 

 the engine, we ought to have them every day. If the overhanging firebox 

 so much objected lo by General Pasley were dangerous, it would be ab- 

 solutely impossible to work the London and Birmingliam one day wilhout 

 a Scries of accidents. The engines upon that line have fireboxes projecting 

 beyond the bearing axle fully 4 feet (i inches, being 5 inches more than the 

 corresponding projection of Ihe Norfolk engine. The Lond<in and Birming- 

 ham line has been worked now uearly eight years with an unparalleled traltic 

 with engines having overhanging fireboxes, without any accident nhiih 

 can fairly be allribuled to such a peculiarity of conslruction. 



I originally objected to this projection of ihe firebox beyond the axle ; 

 but, afler an experiment continued uniulerruptedly for a series of \ ears, 

 with an ernormous traffic, it would be absurd lo reject such practical evi- 

 dence and to hold to such an opinion. 



It was this opinion that led me to the construction of the new long- 

 builer engine, and the abandonment of the objection I originally enter- 

 tained and acted upon. When I considered, moreover, that the Loudiin 

 and Birmingham eii;;ines had, in addition lo the overhanging firebox, a re- 

 markably short beaiiug upon Ihe rail, and, consequently, admittiug of the 

 overhanging weight operating with increased effect, the testimony appeared 

 to me conclusive. 



The London and Birminsham engines in the commencement had a bear- 

 ing upon the rail of only 5^ feel (they have since beeu extended), whereas 

 the Norfolk engines lla^e a bearing of lOJ leet. On this point I need not 

 confine my reference to the engines upon the London and Birmingliam, 

 because they are not peculiar to that line ; they are to be found on many 

 others. 



Whatever may be the effect of such evidence upon Ihe minds of others, 

 I must confess that lo me it Hppears perfectly conclusive that the over- 

 hanging box exercised no influence such as General Pasley imagines. 



In confirmation of this, I may slate that yesterday, with a passenger 

 train of 40 tons, with a boisterous side Wjud, 1 came from Dariinglou to 

 York on the A engine, which has an overhanging box and long boiler, ac- 

 companied bv Jlr. T. K. Harrison, Mr. Fleiclier, and Mr. JosephSle- 

 phenson, for the express purpose of trying the oscillation of Ihe engine. 

 Kor several miles ihe speed exceeded 58 miles an hour, and in some we 

 passed the conseculive quarter mile posts in 15 seconds, being 00 miles aii 

 hour. In addiiion lo the overhanging firebox, we were all standing on llie 

 footplate wiih the enginemaii, excepiing iMr. Joseph Stephenson ; conse- 

 quently, the circumstances were peculiarly calculated lo excite oscillation, 

 if the tendency existed to auy appreciable extent. I am, however, enabled 

 to declare most positively, that this engine was not only entirely free from 

 any dangerous oscillation, but as steady as any engine 1 ever rode upon. 

 Here I will leave the question of o\eihanging firebox and proceed lo notice 

 the next peculiarity of the Norfolk engine specially noticed by General 

 Pasley — viz., ■' The wheels being huddled together." 



In looking at this part of the subject, 1 am relieved from any disciisp.ioa 

 as to mailers of opinion ; it is simply one of dimeiibiou, which admits 

 happily of no dispute. I therefore give >ou the dimension of t^langhter's 

 engine, which Ihr- Cieneral reUiriietl totov\n upon, and declared safe and 

 steady, and lliose of the Norfolk eugiue, which he condemns : — 



Ft. In. 

 Slaughter's engine, distance between extreme axles .. II (i 

 Norfolk eugiue, distance between extreme axles . . 10 B 



