that line. The object of this inquiry was to settle the values of several data or conditions connected with the working of railways, or what might be called Railway Constants.' Among these the most important and the most difficult, was the determination of the resistance to the tractive power. After various unsuccessful attempts to apply dynamometric instruments to the purpose, the following expedient was resorted to, the result of which was completely successful:-The train of carriages whose resistance was desired to be ascertained, was placed near the summit of an inclined plane. An engine placed behind it put it in motion, and dismissed it down the plane with a high velocity. The consequence was not, as might have been expected, that the train descended with accelerated speed. On the contrary, it was found as it descended to be gradually retarded, until its motion was reduced to a certain uniform velocity, which it retained until it arrived at the foot of the plane. Mechanical considerations proved, that the gravity of the train resolved in the direction of the plane, must be equal to the resistance which the train would have opposed to a power moving it along a level.

But on submitting the same train to the same experiment on planes of various acclivities, it was found, that each acclivity gave a different uniform velocity of descent. From this followed the consequence, contrary to all that engineers had before taken for granted, that the resistance to the moving power augments in a very high ratio as the speed increases; and that at the usual speed of passenger trains, this resistance is much greater in amount than any estimate which engineers had previously allowed for it.

*

It was also rendered apparent, that the usual mode of estimating the resistance at so much per ton of the load was altogether fallacious, inasmuch as the same weight of load would offer different resistances to the moving power, according to the number and form of the carriages, and the speed of the motion. * On every species of road, the acclivities which are admissible depend on the average resistance offered to the moving power on the level. If this resistance be great, then a considerable ascent will not be felt,-the additional resistance which it opposes to the moving power bearing an inconsiderable proportion to the whole amount of resistance which that power must at all times, over

* For the details of this investigation, see the Report of Dr Lardner in the Proceedings of the British Association, and the Appendix to the same, by Mr Edward Woods.

come. But if, from the mechanical perfection of the road and the carriages, the resistance habitually opposed to the moving power on the level be very small, (as is the consequence of the admirable perfection of railways,) then a very slight acclivity will be sufficient to disable the moving power altogether. It will therefore be easily understood, that the degrees of ascent which on a common Macadamised road are scarcely felt, are wholly inadmissible on railways worked by locomotive power. The more exquisite the perfection of the instrument, the more inconsistent with its efficiency are even slight defects: gaps and inequalities, which would not sensibly impair the excellence of a knife, would entirely destroy the utility of a razor.

Railways must therefore be so constructed as to be nearly level. An inclination rising at the rate of one foot in fifty would not be distinguishable from an absolute level, by mere inspection, without the aid of levelling instruments. Yet such an ascent would more than treble the resistance of a railway train moving with the usual speed.

If some mechanical causes forbid a railway to undulate, others -render it difficult to wind or to pursue a serpentine course. The necessity for undulation might be avoided, and a general level course preserved, were it possible to carry it along the trendings of valleys and round the bases of hills. This, however, is ren dered impossible, by the mechanical conditions of its structure. A railway carriage moves in a groove, or, at least, in what is equivalent to a groove. Without some violence to its principle, or some strain upon its structure, it is therefore capable of moving only in a straight and direct course. If it has to change its direction, it must be through a curve which bends so slowly and gradually, that the part of it occupied at any moment by the carriage shall not sensibly differ from a straight line. The curve, in short, must be one of very large radius; and even in such a curve the carriage can only be forced to turn by the constant pressure of the flanges of the wheels against the outer rail. This difficulty becomes greater as the speed of the motion is increased. A standing rule of railway Committees in Parliament was, that all curves of less than a mile radius should be matter of special inquiry and report. s

Such are among the causes which have rendered the construcstion of railways expensive, by rendering inevitable vast works sto preserve the necessary straightness, and continuous level of -the course. As the line cannot descend to the level of valleys and rise over the surface of hills, the former must be filled oup and the datter excavated. The road is conducted over the valley on an embankment, and through the hill by means of an excavation. But the valley may be occasionally too deep to

render an embankment practicable, or the earth to form it may not be attainable. In this case, the road is raised to the necessary level by a viaduct or bridge, of height and magnitude commensurate to the depth and width of the valley to be crossed. In like manner, the hill may be too lofty to allow a practicable cutting; in which case, a hole is bored through it of sufficient calibre to contain the railway, and allow trains to pass through, and it is lined with masonry; a tunnel, in a word, is constructed. When the necessity for such stupendous expedients is duly considered, we shall cease to wonder at the enormous cost of railways.

The system of internal communication by railways now in progress of construction throughout Great Britain, will form, under various points of view, a singular example in the history of public works. Their stupendous magnitude, and the many novel works of art upon them, are scarcely so remarkable as the rapidity of their execution, the amount of capital they have absorbed, and the still more enormous amount of capital they have created. The effects they have produced upon the social and commercial relations of different centres of population and commerce, by augmenting in an unforeseen and incredible ratio the personal communication between them, are not among the least memorable consequences of these undertakings. We have stated that the first of this series was the Liverpool and Manchester line-thirty miles in length-which was opened for traffic in 1830. In the year 1840, there were thirteen hundred miles of railway in full operation in England, upon which, during that year, twelve millions of persons had been conveyed. In 1841, fifteen hundred and fifty miles were worked, on which twenty millions of passengers were carried. In 1843, the length of railway open was eighteen hundred miles, and the number of passengers transported nearly twenty-seven millions; and in 1844, the length was increased to nineteen hundred miles, and the passengers exceeded the incredible number of thirty millions!

Nearly sixty millions of capital had been expended in little more than ten years on these enterprises. But all the principal lines paid large profits. Dividends of ten per cent were declared, and the shares rose to cent per cent premium. The demand for railway shares was enormous; and a supply of corresponding magnitude soon met it. In 1845, three hundred miles of new railway were opened for traffic; and acts were passed by the Legislature, sanctioning projects in which the construction of a further extent of eighteen hundred miles of railway was undertaken.

Before we proceed to notice the enterprises which remain to be executed, let us examine a little more in detail what has been already effected, and its results.

*

If we take the principal railways which have been completed and brought into full operation, excluding only a few obviously exceptional ones, we shall find that the average amount of capital which they have absorbed is at the rate of L.35,000 per mile. This amount has, in different cases, been distributed in different proportions among the several heads of expenditure; but the following may be taken as near the average distribution:

The railways constructed with the wide Gauge were more expensive. An extent of two hundred and forty miles, had absorbed L.9,704,368, at the close of last year, being at the rate of above L.40,000 per mile.

Such being the cost of construction, let us consider the service rendered to the public, and the revenue produced.

By the returns published by the Railway Department of the Board of Trade, it appears that the traffic for the three years ending 30th June 1845, was as follows:

Hence we infer the amount of each kind of traffic each year, as follows::

* Such for example as the London and Blackwall, the London and Greenwich, and a few which, on the other hand, have been completed at an exceptionably low rate.

VOL. LXXXIV. NO. CLXX.

21

It appears, therefore, that there is an annually increasing amount of traffic; that the rate of increase on the Goods traffic, is even more rapid than the Passenger traffic; and that the average annual total amount received per mile, in 1845, was L.3000, omitting fractions.

The proportion of this gross revenue, absorbed by the current expenses of the transport, is different on different lines. In some it is above 50 per cent; in some below 40 per cent. In 1842 it was estimated at 44 per cent of the gross revenue; but it is probable that, by improved machinery and increased economy, it is now diminished. It may be taken at present at 42 per cent of the revenue. Of the L.3000 per mile received then, 58 per cent, or L.1740 per mile may be taken as the profit on the L.35,000 per mile sunk-being at the average rate of 5 per

cent.

Thus, it appears, that although several great enterprises give per cent, the general average profit on these speculations does not amount to more than the ordinary profit on capital engaged in large commercial investments. Many unsuccessful lines pay little or no interest on the capital sunk, and some yield dividends of comparatively small amount; and thus the larger dividends of the more successful lines are neutralised. The increase of traffic, however, indicated in the above table of annual returns, would render it probable that the annual profits would become larger, unless the further extension of railways should check them.

It will be observed that of the total annual revenue of the railways, 63 per cent proceeds from passengers, and 37 per cent from goods.

In estimating the manner in which the railways minister to the public service, the question arises-whether they chiefly serve as means of personal intercourse between those great centres of population and commerce which are usually selected as their termini; or, whether they in a greater degree benefit the population located in those districts of the country through which they pass. Unquestionably the general impression was, and, so far as we have observed, still is, that the great mass of their traffic is derived from the large cities and towns at their termini. This question has much interest, not merely to the public in general, but to those who engage in railway speculations in particular. Is the population of the country through which a line of railway passes, or the population of its termini, to be considered most in calculating its probable success?

We shall arrive at a solution of this problem by comparing the total number of passengers carried on the railway, with the