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THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



TA^E I. 



RKSILT OF THE PERFORMANCES OF THE DIFFERENT ENGINES ON THE 

 GREAT WESTERN RAILWAY. 



TABLE II. 



TABLE OF THE RELATIVE POWERS OF THE DIFFERENT ENGINES ON 

 THE GREAT WESTERN RAILWAV. 



It may be here remarked, th.it unless very large anil heavy tenders are con. 

 vcyed with the eni;incs, the stages cannot be of a much longer distance than 

 twenty miles ; the quantity of water evaporated in this distance, by the North 

 .Sior Engine, being upwards of three tons. 



The performance with the North Siar was wiih a six wheel, and a four 

 wheel passenger carriage, capable of containing 56 passengers; the experi- 

 ment with the Apollo Engine was with a six wheel carriage capable of con- 

 taining 32 passengers, the full complement of luggage in both cases being 

 allowed. 



It is scarcely necessary to state that, this is a load which cannot be considered 

 a profitable or adviseablc one, to be fixed upon as a standard for the weight of 



the trains ; or such a load as should be considered to be the weight of the first 

 class trains on the railroad for permanent adoption. It is only necessary to re- 

 fer to the experiments to see, at what a sacrifice of poiver and consumption of 

 coke this rate has been accomplished, to arrive at once at the conclusion, that 

 if such a rate of speed cannot be kept up excejit at such a sacrifice, the rate 

 must be reduced. 



The .'Eolus engine with 24 tons, realised a rate of .37 miles an hour, and the 

 twelve inch cylinder engines with 18 tons, accompli.'hed a similar p rformance ; 

 these are likeqvise loads below that which it will be necessary to provide for 

 the regular traffic of the railway. 



We come now to the next load, on which experiments were made, viz. 32 

 tons; this would provide accommodation for about 1 12 people with their lug- 

 gage, with 2 six, and 2 four i^ecl first class carriages ; and with this load the 

 North Star accomplished a rate of nearly 37 miles an hour, and the other 

 engines about 34 miles. This is likewise a less load than can be reckoned 

 upon for the permanent working of the line, as it does not allow for the con- 

 veyance of pi ivate carriages, which must always be calculated to accompany 

 the swift or first class trains. 



Wiih a load of 50 tons, ihe speed realised by the Northern Star is nearly 

 35 miles an hour; — with the Oiolus 32 railcs ; — but with the other engines 

 only 2C^ miles an hour. 



When the load is increased to SO tons, the North .Star engine performs a 

 rate of nearly 33 miles an hour ; but the performance of the (Eolus engine is 

 diminished to '2-li miles an hour ; and we sec that a rate of 22^ miles an hour 

 is the performance of engines such as the ^'erus, Neptune, and Apollo, with 

 12 inch cylinders, and 6 and 7 feet driving wheels, respectively. 



It docs not appear, therefore, that with the best of the engines at present 

 upon the Great Western Railway, a greater velocity can be calculated upon ; 

 at the mean maximum rate of speed than -35 miles an hour, with such loads as 

 may be expected to constitute a first class train. For extraordinary purposes, 

 with a diminished load, a rate of 40 miles may be attained, but looking at all 

 the circumstances incidenlal to railways, with engines and trains travelling at 

 the maximum rate of speed, it does not appear to rac, that any standard equal 

 to 40 miles an hour can be depended upon in practice Ihe weight of two first 

 class carriages, one with si.x wheels, and one wiih four wheels, and of two 

 second class close carriages, one with six wheels, and one with four wheels, 

 with their complement of passengers and luggage, will weigh about 31 tons; 

 but this docs not allow of any trucks for the conveyance of gentlemen's 

 carriages, or for horse boxes. Upon the London and Birmingham Railway, 

 since it has been opened throughout, the average weight of the trains, including 

 passengers, passengeis' carriages, carriage trucks, horse boxis and luggage 

 vans, has been about G5 tons ; this includes both first-class and mixed trains, 

 the former being upwards of 50 tons and the hatter about 70 tons. Taking 

 this as a standard for the Great Western Railway, it does not appear that, for 

 the first-class trains a less weight than 50 tons can be calculated upon ; and 

 with this weight the experiments show tliat a mean rate of 35 miles an hour 

 between the stages, after getting up the speed, and bofore its being checked 

 may be accomplished, under circumstances similar to those experienced during 

 the time these experiments were in being performed, and with engines of the 

 power of the Nonh Star. And it will be seen that with a load of 80 tons, which 

 would not much exceed the weight of a second class train, a velocity of nearly 

 33 miles an hour can be maintained, during the time the engine is at the full 

 rate of speed. 



Taking 35 miles an hour, therefore, as the mean maximum rate of speed 

 between (he stages, it will have to be considered what general average rate 

 can be kept up between one end of the line and the other ; in this calculation 

 we have to take into account, the time lost in getting up the speed, and in 

 stopping the train, the time lost at each station, and all the vicissitudes of 

 wind, weather, and incidental casualties. On the other hand I think it my 

 duty to explain, that these ex| eriments, which are here brought forward .as a 

 standard for the assumption of this rate of speed on the Great Western Railway, 

 though it is not expected that more weight should be placed upon them than 

 upon experiments generally, which must be considered as exhibiting more 

 favourable circumstances tlian tlie everyday practical result ; yet it must be 

 taken into account, that the road for three or four miles fiom one end of the 

 line was under repair, and would not therefore present what may be considered 

 an average result, or what may be expected to be the permanent result when 

 the road is in the best possible order. We shall see alterwards to what extent 

 this may be supposed to influence the general result ; I thought it my duty, 

 however, to mention it in this place, that every circumstance connected vvitii 

 the enquiry likely to operate, in any degree whatever upon the general result, 

 should be brought into consideration. 



On a mere inspection of these tables, every person must be struck with Ihe 

 enormous increase of power required to eflTect a high rate of speed, or a rate 

 of 40 miles an hour, compared with that which is required to propel a load M 

 the i-ateof about 20 miles an hour. We see the Noilh Star engine, dragging 

 166 tons at the mean rale of 23.3 miles an hour ; while the same engine under 

 similar circumstances is only capable of dragging 15 tons at the late of 41.15 

 iniles an hour. Again the /EdIus engine, drags 104 tons attlie rate of nearly 

 23 miles an hour ; and only 24 tons at the rate of 37.28 miles an hour. The 

 engines of less power exhibit precisely the same results, we see them dragging 

 50 tons at 2Ci miles an hour, and only nine tons at 40tV miles an hour. 



If this had been the result of theoretical deduction, some suspicion might 

 have existed of its accuracy, but the above is the result of cai-efully-conducted 

 experiments, made under precisely similar circumstances; and although it 

 might have been desirable that a greater number of experiments had been 

 made in corroboration, tlieie can be no doubt that the results os shown by 



