THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



67 



STstems of working tlie railways at present in use, and wliicli may be eonsi- 

 (lereil as tlie practical result of the eflect of the trains on tlie rails ; still, if we 

 wish to know the actual comparative firmness of base, we must take into ac- 

 count the relative incumbent weights of the respective trains. I have not yet 

 been able to obtain the pressure upon the rails of the Great Western Railway 

 by the engines, tliere being no weighing machines on that raihoad by which 

 this could be ascertained, when these weights are kiiowu, the comparison can 

 then be made with the engines ; the weight of the carriages are known, and 

 th.> comparison can therefore be made with them. The weight on each wheel 

 of the (ireat Western llailway carriages may be taken at about 1-5 tons, and 

 oi' the carriages on the other railways at !• 12.1 tons; and consequently the de 

 flections have been produced with incumbent weights, in the proportion 

 of 4 : 3. 



We coni'^ now to the effjct which the piles have upon the firmness' of base 

 of tlie continuous timbers on the Great Western Railway ; the reasons as- 

 .'<igned by ^ir. Brnnel for adopting piles was, for the purpose of securing and 

 holding the timbers down to the ground witli much greater force than merely 

 the weight of the timber itself, and thereby to effect a closer contact between 

 tlie timber and the ground. It became, therefore, necessary to ascertain whe- 

 ther the timbers were lield down to the ground, or if they were supported by 

 the piles. To accomplish this, the instruments were first of all applied to the 

 rails with the piles in action, or without being disturbed, and the deflections 

 taken ; tlie transoms were then divided near to the timbers, or between the 

 timbers and the piles, the instrum>>nts remaining applied to the rails, and the 

 effect produced by the separation of tlie timbers from the transoms was thus 

 obtained; in almost all, if not in every case, the timbers fell, on the transoms 

 l>''*ing divided, showing that the action of the piles was not to hold down, but 

 to support the timbers. Tiiis was also shown very conclusively in the effect 

 exhibited by the diagram* taken, before and after the transoms were divided ; 

 — (he first diagram taken after the transoms were divided, showed a greater 

 amount of deflection from the original line of the rails, than when the pilis 

 were in action ; it was found, however, that the rails diil not rise to tlieir 

 original level, but that, in fact, a permanent depression to a certain extent had 

 taken place; — in continuing the experiments the di'flectiou became less, show- 

 ing quite decisively, that the timbers were supported by the piles, and that 

 they were not in fact ill such close contact with the ground when attached to, 

 as they were after being detached from, the piles. This was the result in 

 every instance. Most of the diagrams were taken upon that part of the line 

 near to Paddington wliich had been recently packed, and being clayey 

 ground presented a wet and spongy base, and the packing was not so perfect 

 as in some other parts of the line ; the extent of the deflections on this part 

 should therefore be taken as being more unfavourable than an average result ; 

 liut on applying the instrnments to a part of the line, selected as being in the 

 best order, tlie same relative results were exhibited ; the timbers dropped on 

 their division from the transoms and piles, and it was found tiiat the amount 

 of deflection was less after the piles were detached than before, after the train 

 hail run along the rails for a few times. 



Some iiart of the Great Western Railway is laid with continuous timbers, 

 without piles ; an experiment was made upon this, where the ground was not 

 the most favourable, or similar to that where the diagrams were generally 

 taken with piles, and deflections similar to the above were obtained ; — an ex- 

 periment was however made, and several diagrams taken, upon an embank- 

 ment with timbers without piles ; when the result was an amount of deflection 

 much less than that where the piles were in action, and very little, if at all, 

 inferior to that of stone blocks, taking into account the difference of the insist 

 ent weight. At this place, however, the scantling of the timbers was greater 

 than ordinary, being ten inches in depth, the general depth being six to seven 

 inches. 



The experiments on the Manchester and Bolton Railway, it will be seen, 

 exhibit a coivsiderable amount of deflection, quite as much, if not greater, 

 than that of the Great Western generally, taking into account every circum- 

 stance of the scantling of timbers, section of rails, and weight of the engine 

 and trains. 



The result of the whole of these experiments is, that stone blocks afford the 

 firmest base ; and that there does not exist any material difference of defli'c- 

 tiou between longitudinal timber bearings with a continuous rail, and cross 

 timbers with isolated supports ; the difference, if any, being in favour of con- 

 tinuous bearings. 



The previous observations apply to the vertical deflection only, during the 

 progress of the experiments on all rails resting on chairs, it was ibund that in 

 a great many cases the rail was deflected inwards, the great majority of cases, 

 however, being outwards ; it has been, therefore, extremely difficult to reduce 

 the results into a tabular form, some of the diagrams exhibiting both inward 

 and outward deflection in the same experiment. The cone of the wheel hav- 

 ing a tendency to press the rail outwards, and also the action of the flange 

 having the same tendency, it is quite clear that when the deflection is inwards, 

 it must be the result of some accidental cause ; a want of solidity of the base 

 of the blocks or sleepers on the inner edge, or from the rail not bearing hori- 

 zontally in the chair, or at the proper inclination to the cone of the wheels. 

 Upon the Great Western Railway, the horizontal deflection was invariably 

 outwards, and this is no doubt owing to tlie particular construction of that 

 road ailmitting of a more perfect and pernianent adaptation of tlie rail to the 

 cone of the wheels. Want of time precludes me from going into the particular 

 results, exhibited by these experiments on horizontal deflection ; the general 

 result, however, appears to be, that they assimilate very nearly to the vertical 

 deflections, both in their nature and extent, on the different descriptions of 

 bearings. 



The remaining part of this inquiry is the latter part of the third proposition, 

 Tiz. ; whether a greater steadiness and smootliueiis of motion is produced to 



the carriages, and to what extent, on the Great Western Railway, by ttis 

 increased width of gauge. 



Tlie solution of this question also appeal red capable of being subjected to 

 the test of experiment, although not without considerable difficulty. The mo- 

 tion of carriages on railways being the effect of so many distinct causes, it was 

 extremely difiicult to contrive an instrument to detect and record each motion 

 separately. 



For instance, any sinking of the blocks, or supports of the rails, or the 

 deflection of the rails themselves, produce a corresponding depression of the 

 wheels of the carriages on that side where s;icli yielding lakes place ; — the 

 subsidence or shrinking of tlie base, or formation level of the railway, gene- 

 rally produces also an inequality of level on the two sides of the railway ; and 

 these variations of level between one side and the other, tend to produce a 

 continual rocking motion in the carriages transversely, which is aggravated 

 more or less in proportion to the frequency and extent of these inequalilies of 

 level of the two sides of the railway. The same causes, viz. the inequalities 

 of level, likewise produces a pitching or undulating motion, longitudinally ; 

 and those two motions combined, the nndulatory motion in the direction the 

 carriages are travelling, and the rocking motion traversely, produce a vertical 

 motion. Any change likewise in the direction of the road, throws the car- 

 riage wheels from a straight line against the interior side of the curve, and 

 thus produces a lateral motion of the carriages, and when the curve again 

 changes, or the line of direction becomes straight, the wheels are tlironu to 

 the opposite side of the rails. The difference of level between the rails on 

 the two sides of the railway, besides producing a rocking motion transversely, 

 causes the carriages to vibrate from side to side, in proportion to the extent 

 of the inequality of the level ; the depression in the first instance causing tho 

 carriages to fall towards that side of the road, and the fl.anch of the wheel t) 

 press against the rail, the conical form of the wheel immediat*:ly throws it 

 off towards the opposite side ; and we thus have a continual contest 

 between the gravitation occasioned by the difference of level between the 

 two sides of tlie railway, and the line of direction incidental to the 

 conical action of the wheel; — As these effects are continually in action, 

 we hence find that the lateral oscillatoi-y motion is the most predominant of 

 all the varieties of motion which occur on railways; and when a very liigli 

 rate of speed is attempted, this lateral motion is very considerably increased, 

 so much so that in extremely high rates of speed a sort of swinging lateral 

 motion is produced, the carriage wheels on each side being thrown alternately 

 back and forwards against the sides of the rails : — probably from the cone of 

 the wheels, not having lime, in extremely rapid velocities, to accommodate 

 itself to the proper line of direction. 



t'onsidering, tlierefore, the variety of motions in action at the same time in 

 railway carriages, the different causes by which these are produced, and the 

 numerous adventitious circumstances operating to increase, modify, or coun- 

 teract them, it is not to be wondered that a difference of opinion should e.risf 

 in the public mind generally, as to the relative smoothness of motion of 

 railway eaniages on different railroads; — an increase of a lew miles per hour 

 in tlie velocity, not perceptible to a traveller, will make a considerable variation 

 in the motion ; — the number and nature of the curves ; — a difference in the 

 construction of the carriages; — the position of a carriage in the train ; — ^or 

 even difl'erent bodies of the same carriage, all tend to influence the aggregate 

 amount of motion in a railway carriage ; and few, if any, of the causes 

 whereby these different motions are produced, are sensible to the observation 

 of a passenger, at least to the gi-eat majority of passengers ; they judge from 

 the quantity of motion, without reference to the causes, and hence the differ- 

 ence of opinion, which has arisen as to the comparative smoothness of motion 

 on some of the existing railways. 



To the most attentive observer, knowing all the causes which produce these 

 variety of motions, it would be extremely difficult, if not impossible, to judge 

 from observation of the relative smoothness of motion, or at any rate of that 

 which properly belongs, or has reference to, tlie construction of the railway. 



These circumstances, therefore, rendered it almost absolutely necessary to 

 subject this part of the inquiry to experiment, it not appearing possible to 

 arrive at any conclusive determination by common observation ; and after 

 considerable "difficulty a set of instruments were contrived, which sulijected all 

 the different motions of railway carriages to experiment, and which produced 

 diagrams of all the oscillations of the carriages from one end of the Une to 

 to tlie other. 



The different kinds of motion produced on railway carriages may there- 

 fore be comprised within the follow iiig heads, viz. : — 



1st. A rocking motion transversely, produced by the inequalities of the 

 level of the two sides of the railway. 



2ud. A pitching or vertical motion, in the centre of the carriages, being the 

 combined action of the alternate rocking motion of the two sides of tile car- 

 riages, produced by the undulations of the load. 



iid. A lateral, or oscillatory motion horizontally, produced also by the 

 inequalities of the road, and tlie other causes previously enumerated , throwing • 

 the carriage wheels from side to side against the rails. ... 



Having thus, agreeably to your instructions, and to the extent to wliicIi 

 the time and opportunities afl'ordi'd has enabled mo to accouiphsb, iiivesti 

 gated by experiiiu-utal data and in(|uiries all the properties of the system of 

 construction and working of the Great Western Railway, I now beg to lav 

 before you the conclusions wliidi appear to me to be the result of these in- 

 vestigations. I tliink it my duty however, in this place, to represent to you 

 that I have not been able, in draning out tliis report, to avail myself fully of 

 the vast mass of valuable information elicited in the ccuirse of this inquiry, 

 owing to the short period, (only six days,) between finishing the experiments 

 and behig reciuired that the report should be printed; and I trust that this 

 will bo a sufficient excuse for the impeil'eot manner iu which it is presented 



