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grasp of the statist since the publication of our papers on the subject in 1877 and 1878.

If a series of unattached bodies are compelled to travel in the same path, collisions between them can only be avoided when they move in the same direction, and at the same speed. This simple dynamical law underlies the whole working of the railway system.

Railway trains may be made to travel over the same track in opposite directions alternately. They can only do so in perfect safety by one arrangement,-that of the staff, or permit, which ensures that only one engine shall be on the same section of a line at a given time. But the amount of work that can be done on this system is small.

For the passage of trains over the same line, in the same direction, at different speeds, no absolute rule of safety exists, although the efficient working of the block system produces an approach to safety. In this case the work done, as well as the danger incurred, mainly depends on the ratio between the different speeds. Thus the London and North-Western Railway run passenger trains timed at 40 miles per hour, and mineral trains timed at 15 miles per hour. For one of the latter to get out of the way of one of the former, starting 15 minutes later, there must be a siding every 74 miles. In point of fact, between Camden Town and Hillingdon, a distance of 75 miles, there are 10 waggon sidings. But the risk incurred by the entrance into and exit from these sidings is considerable, and the speed and number of the passenger trains must be proportionately limited, when only two lines of way are provided. Four lines, in consequence, have now been laid for 80 miles on this railway.

In all cases of doubling the lines of way, opportunities of collision will arise at stations, unless the goods and the passenger lines are so distinct as to prevent the slow and the fast traffic from ever passing over the same points. Great relief to the traffic may be obtained by doubling the way; but this source of danger can never be entirely obviated so long as the stations are common to the two descriptions of trade.

At the opening of the London and Birmingham Railway in the year 1840, 28 daily trains in each direction were all that were required or run. The average gross load of each journey was 40 tons for a passenger train, and 98.67 tons for a merchandise train. The average speed of the former was 25 miles per hour, that of the latter 20 miles per hour. Thus there was an interval of 51 minutes between the departure of any two successive trains, taking an average through the twenty-four hours. And by a moderate extension of this mean interval between the starting of a goods and of a following passenger train, the latter would be prevented from catching the former before arriving at the terminus.

With a double road, carrying this small amount of traffic, it seemed to be at the same time safe and desirable to attract as much trade as possible to the line. And any traffic that would pay a small

net profit, after defraying all its own expenses of every kind, was thus worth securing; as it would pay something, however small, towards the interest of capital, by occupying time that would otherwise have been lost to the company.

The line of policy thus adopted has ever since been maintained by railway managers, in spite of the widely differing circumstances of the present time. Mr. Robert Stephenson, who declared that a cheap passenger tariff, with ample accommodation, was the great point for railway directors to study, and that the carriage of minerals at the freight of one-halfpenny per ton per mile was a positive robbery of the carrying company, still admitted the utility of mineral transport in rural districts. But when, as became the case in 1875, 127 trains each way ran through the Primrose Hill tunnel, instead of 28 (and that without counting the short local trains); when the weight of the passenger trains was increased from 40 to 257 tons, and the speed from 25 to 40 miles an hour, at the same time that the weight of the mineral trains was increased to 540 tons, and the speed reduced from 20 to 15 miles per hour, it became evident that rules which were well considered in 1840 had become wholly inapplicable. Little more than II minutes could elapse, on the average, between the starting of two successive trains. But in 12 minutes, while a mineral train only advances 3 miles, an express train advances 8 miles. Thus even the allowance of a waggon siding every 7 miles became inadequate, and the London and North Western Company was put to the expense of laying four lines of railway for 81 miles out of London, and three lines for 34 miles further.

It may here be remarked, as illustrating the demand on the capital, as well as on the occupation of the line, due to each description of traffic, that in 1875, out of 1,935 locomotives possessed by the London and North Western Company, only 391 were passenger engines; and of the remainder 171 were constantly employed in the process of shunting and marshalling the goods and mineral trains. Roughly stated, the capital invested in plant for the passenger traffic will thus have cost about 1,500,000l., and that for the goods and mineral traffic, 6,000,000l., or in that proportion. The gross earning of each passenger engine in 1875 was 9,555, that of each goods or mineral engine was 2,772/. Thus the distribution of the capital in plant should be regarded in ascertaining the value of each kind of traffic.

In volume xxxviii. of the 'Minutes of Proceedings of the Institution of Civil Engineers' for the session 1873-1874, is a chart, or diagram, of the working time-table of that portion of the Great Northern Railway which extends from London to Peterborough. The course of each train is drawn on this chart, the various kinds of trains being distinguished by different colours. The distance is 76 miles, which is covered by the most rapid express train in 1 hour and 25 minutes, or at the rate of 1 mile in 112 minutes, or 53.6 miles per hour. No. 612 (No. CXXXII. N.s.) 3 G

The slowest goods train occupied 6 hours 50 minutes, being at the rate of 1 mile in 5.4 minutes, or IIII miles an hour.

Nineteen passenger trains occupied the line for an aggregate of 35 hours 40 minutes; 19 goods trains occupied the line for 72 hours 36 minutes; and 33 coal trains occupied the line for 140 hours 35 minutes, according to the table, during the same 24 hours. This refers to through trains alone. Thus the actual occupation of the way and stations of the company (without making any allowance for the extra length of the mineral trains) was in the ratio of 14′6 per cent. for passengers, 29.4 per cent. for goods, and 56 per cent. for minerals. In the year 1875 the gross earnings of this line were 42'5 per cent. from passengers, 36.40 from goods, and 17.10 from minerals. Thus 56 per cent. of the capital of the line was occupied in earning 17.10 per cent. of the gross profits. What share of the net profits that percentage represents the accounts do not show; but it has recently been generally admitted that the mineral traffic is a 'poor paying' business.

The ruling gradient of the Great Northern Railway is one in 100. Over a line of this inclination the most economical rate of travelling is about 30 miles per hour. The goods trains are under this economy of speed, averaging a mile in 32 minutes. The mineral trains average a mile in 3.62 minutes. But the ratios are not uniform. They are made up of rapid running and stoppages. The fuel expenses are increased by the former, and the wages expended by the latter, so that the mineral traffic is thus conveyed at a greater cost per ton mile gross than the goods traffic. Of the passenger trains 12 require an average time of 1 hour, and 7 an average time of 2 hours 38 minutes, to run the 76 miles, being at the rates of about 50 and 29 miles an hour. The cost of the slower trains will be, per ton mile gross, close upon that of the goods trains; that of the 50 mile per hour traffic will be about 27 per cent. more than the most economical speed. At 10 miles an hour the cost per ton mile gross is half as much again as at the most economical speed.

Thus the mineral trains, weight for weight, cost rather more than the most rapid passenger traffic, on the assumption that all the charges of the line are equally divided over the gross tonnage carried over the rails. It may be added that the coaching stock of the company requires 9 miles of line for standing room, and the waggon stock requires, exclusive of the lengths of line required for sorting and shunting, 50 miles; this is exclusive of any vehicles not the property of the company.

On the London and North Western Railway, according to statements to be found in vol. xli. of the Proceedings of the Institution of Civil Engineers,' the proportion of time occupied by the different descriptions of traffic over the 79 miles from London comes out at 43 per cent. for mineral trains, 34 per cent. for goods trains, and 23 per cent. for passenger trains. But this is taken from the running speeds mentioned by Mr. Findlay, and not, as in the case of the

Great Northern traffic, from the total time consumed between the termini. The correction due to the latter consideration will bring the percentage very near to that of the Great Northern traffic.

Thus, whether we regard the interest on the capital invested in plant, the earning per locomotive, or the proportion of time for which the line of a railway is occupied by the respective kinds of traffic, we find a difference of from three to four, or even five to one, in the gross earning power of the passenger, as compared with the non-passenger, traffic. In the case of the Taff Vale Railway, which has been especially laid out for a mineral line, where the freight is not kept down by competitive sea or water carriage, where the waggons have an exceptional carrying capacity in proportion to their weight, and where the carriage of the minerals is chiefly effected by the force of gravity (the locomotives bringing back the empty waggons), a single pair of lines of way has been found inadequate to carry a mineral and merchandise traffic of under 5,000l. per mile, together with a passenger traffic of under 650l. per mile. On the other hand, the Metropolitan Railway carries a traffic of 36,600l. per mile, and the Metropolitan District one of 34,000l. in passengers alone, the former contriving to earn a further 2,000l. per mile from merchandise traffic. Thus, as far as our experience goes, the earning capacity of a passenger line is at least sevenfold that of a non-passenger line. And the Metropolitan engines earn more than 12,000l., and the Metropolitan District engines more than 10,000l. each per annum; while in the only case in which we have the particulars of the respective earnings of non-passenger engines (with the exception of the lines worked by gravity) the annual earning does not reach 2,000l. apiece.

Comparing, then, the outcome of our English practice, the carrying capacity of a passenger line is sevenfold that of a non-passenger line, and the earning capacity of passenger plant (per 100l. of the cost) is fourfold that of non-passenger plant. This refers to gross earnings alone. We have yet to inquire into the proportionate net earnings to be derived from the different descriptions of traffic.

The main difference in the cost of conveying different descriptions of freight, whether passenger or goods, arises from the propor tion of tare, or dead weight, to the paying load. There is, indeed, a considerable difference in the cost of speed. But this difference is not in favour of very low speeds. At from 25 to 35 miles per hour, on a line of easy gradients, there is but little difference in the cost per ton of the train. Above or below these rates the cost increases, being close upon the same figure at 15 and at 50 miles per hour. And if a mean speed of 20 miles per hour is made up by running at 30 miles and by waiting at intervals in the sidings, the cost will be 7 per cent. higher than that of a 30 miles per hour train. Thus, instead of diminishing expense by diminishing the speed of mineral trains below the normal most economical rate of the given line, working cost

will be increased by such retardation, and that without taking into account the increase due to the demand for interest on capital.

Mr. Robert Stephenson, in his inaugural address as President of the Institution of Civil Engineers, pointed out that the cost of carrying a ton of goods must always be more than that of carrying a ton of passengers, as the latter load and unload themselves, as well as carry themselves to and from the platforms of arrival and departure. Thus, excepting in the case of speeds considerably exceeding 35 miles an hour, the conveyance of a ton of loaded goods train will always at least equal, and may considerably exceed, that of the conveyance of a ton of loaded passenger train.

The average proportions of paying load and of dead weight in the mineral waggons of the four great trunk mineral carrying lines-the London and North Western, the Great Northern, the Midland, and the North Eastern- allowing for the return of the waggons empty, are 44 tons of load to 56 tons of tare.

The average proportions of paying load and dead weight in a normal passenger train on the above railways (according to the data given in the Report of the Commission on Railway Accounts' of 1877) are 16:45 tons of load, to 83.55 tons of tare, supposing each seat to be full.

The railway returns give no information as to the average proportion of full and empty seats in a passenger train. On the French railways about one seat in four is filled. If we adopt that average the passenger tare will amount to 95.89 per cent., and the net load to 411 per cent. In France the passenger tare is 945, in India 88.2, in the United States, on 3 lines, 94°5; and in New South Wales 93 per cent. of the gross load.

If we assume that at the low rate of one halfpenny per ton per mile coal can be carried on an English railway without either profit or loss, the cost of running a train of 175 tons gross weight will be 38.5d. The receipts from that train, if loaded with coal (up and down mileage included) will also be 38.5d. But, taking the passengers at only a penny per mile each, the earning of a passenger train of 175 tons gross weight, one quarter full, will be 108d, and the net profit 69.5d. In a passenger train a little more than half full, a fare of one-sixth of a penny per passenger per mile would be the equivalent of a charge of one halfpenny per ton per mile for the carriage of minerals.

The general outcome of the above facts is to the following effect :— In localities where there is no competitive water carriage, a mineral traffic may be carried on at remunerative prices, and to an amount (as far as our experience goes) of gross income not exceeding 5,000l. per mile per annum. The proportionate profit on the traffic will depend on the rate of freight that the mineral will bear.

In lines of small traffic, it may be advantageous to carry a portion of mineral or other low-paying traffic at rates that afford but a small profit, if it is certain that there is a profit honestly earned after

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