The Semmering line, which lies south of Vienna, on the way thence to Trieste, and which, until the completion of the Brenner, was unique in the boldness of its conception and execution, as also for the height to which it attained, is now eclipsed as to altitude in more than one instance; but as a magnificent engineering achievement it can hold its own against any railway at present constructed. While resembling the Brenner in many particulars, it differs from it in some important points. Among these differences is the fact, that whereas the Brenner line actually surmounts the pass, the Semmering, on reaching a height of two thousand eight hundred and ninety-three feet, or about four hundred feet short of the summit, suddenly, as if tired of so much climbing, plunges into the ground, and only emerges again nearly a mile off, and on the other side of the pass, which it then proceeds to descend. It is thus that it may be said to have been the prototype of its great successor, the Mont Cenis.
The Semmering further differs from the Brenner in what may perhaps be considered its most remarkable feature—namely, its viaducts. For while the latter avoids many a yawning abyss by some ingenious curve, the former seems almost to seek the opportunity for a magnificent display of span. These viaducts occur frequently, being as many as fifteen in number; and in many instances are formed of a double row of arches, one standing on the other in the manner sometimes adopted by the Romans in the construction of their aqueducts. To realise the grandeur of these viaducts, they should not be seen merely from a train, but the traveller should contrive to view them from below. The finest is over the Kalte Rinne, and consists of five arches below and ten above. The line also in places requires to be protected from avalanches of stone or of snow, and this is effected by means of covered galleries, such as may be seen on so many Alpine roads. The tunnels too are as numerous as the viaducts. In fact the train no sooner emerges from a tunnel than it finds itself skimming over a viaduct, only to plunge once more into a tunnel or a gallery. The device for crossing a lateral valley described above in the case of the Brenner is also resorted to here, and need not be further alluded to.
The proportionate cost of the Semmering railway was more than double that of the Brenner, being about sixty thousand pounds per mile. This may be accounted for partly by the fact, that the former was constructed and opened thirteen years prior to the latter; by which the latter was enabled to reap the benefit of the engineering experience acquired in the progress of its predecessor. But the chief cause of this enormous difference in the cost of construction lies in the different modes adopted for overcoming obstacles; and the vast viaducts of the Semmering entailed an expense which was wisely and ingeniously avoided in the construction of the Brenner.
The gradients, as may be supposed, are very steep on both these railways, and the rate of speed not great. On the Semmering a long train has to be divided into two or three portions, to enable it to surmount these steep slopes, which frequently are as rapid as one in forty, even on the viaducts and in the tunnels. The reader has only to notice the numbers on the gradient indicators by the side of an English railway, to be able to judge what an incline of one in forty is like.
But if one in forty seems steep, what shall be said of one in four, which is the gradient of a large part of the Rigi railway? No doubt the ascent of the Rigi has come to be regarded much as the Londoner regards the ascent of Primrose Hill; though in the latter case the hardy traveller has to use the means of locomotion with which Nature has provided him in order to reach the summit; while in the former he merely seats himself in a railway carriage at the base of the mountain, and is deposited without the smallest exertion on his part at or nearly at the top.
Steam here, as elsewhere, has almost entirely superseded the old means of travel. But as if it were not a sufficiently stupendous undertaking to have one railway to the top of a mountain, two have here been constructed, one having its base at Art on the Lake of Zug, the other at Vitznau on the Lake of Lucerne. Taking the latter, which was first accomplished, the height to be scaled is four thousand four hundred and seventy-two feet from the level of the Lake of Lucerne, the total altitude of the mountain being five thousand nine hundred and five feet above the level of the sea. Of this four thousand four hundred and seventy-two feet, the rail accomplishes all but one hundred feet or so. To do this, an excessively steep gradient must be constantly maintained, as the formation of the mountain does not admit of wide sweeps, détours, or zigzags; but the course pursued is round the shoulder, then along the ridge which communicates with the topmost heights, and finally up those heights themselves, a distance of not more than eight miles. It is thus that a gradient of one in four becomes a necessity. Let the reader mark out a distance of four feet, and at one end place a foot-rule perpendicularly. A line drawn from one end of this distance to the top of the rule at the other end will indicate the gradient of one in four. It is a steeper incline than horses and carriages are expected to surmount, yet trains pass up and down constantly without difficulty, and it is confidently asserted, without more danger than on ordinary lines. The rate of speed is of course not high, one hour twenty minutes being occupied in the ascent, and a slightly less time in the descent.
The construction of the train is remarkable. It consists of an engine with small tender and but one carriage. An ordinary locomotive would be powerless on such steep gradients, therefore one of peculiar construction is used, which is of itself an extraordinary object. On level ground it appears as if it had completely broken down and lost two of its wheels. This arises from the fact that, being expressly intended to work on an incline, it is built in such a way as to compensate for the incline and maintain the boiler in a vertical position. This boiler in appearance resembles nothing so much as a large beer bottle standing upright when the train is ascending or descending, but very much out of the perpendicular when on level ground. The small tender is of course constructed so as to have its floor level when on the incline. Its sides are of wire-work, and are made thus with the object of reducing the weight as much as possible; an object which is also carried out both in the engine and in the carriage, which are as light as they can be made, it not being necessary to prevent the wheels jumping from the rails by the pressure of great weight as on ordinary lines, where a high rate of speed is attained. This tender, in addition to its usual functions, performs the office of carrying surplus passengers on an emergency.
The carriage is an open car, rather resembling a block of low pews taken from a church, placed on wheels, and surmounted by an awning, with curtains to let down at the sides, as a protection against the weather. The seats, which are nine in number, and accommodate six persons each, all face one way—namely, downhill; and a fixed footstool serves to keep the passengers from sliding off their seats. Contrary to the usual order, the carriage on this line precedes the locomotive in the ascent, and is pushed instead of being pulled up the incline. In the descent the locomotive takes the first place, and exercises merely a retarding force. It will be seen, therefore, that the two portions of the train are necessarily in close connection when in motion, and for this reason, as well as for purposes of safety, couplings are dispensed with. Each portion is provided with its own brake-power, so that in the event of the engine getting beyond control, the carriage can be stopped and rendered entirely independent, since it is not coupled to the engine. The brake is of course of a totally different kind from that in ordinary use, which would be of no service whatever on such inclines, as the wheels, even if the brake were so powerful as to stop their revolution, would slide down the hill by the mere force of gravity. Here, however, the brake consists in an ingenious adaptation of the means which are employed in driving the engine.
The roadway is laid with three rails, the outer ones being of the usual kind, while the central one is a long-toothed rack, of which the teeth are perpendicular. Into this rack fit the teeth of the pinions or cogged-wheels with which both engine and carriage are provided. Now it is apparent that if these wheels are put in motion they will pull the train along the rack; and if stopped and held firmly in one position, they will prevent any onward motion by the mere clinching of the teeth, to use a common expression. One of the cogged-wheels, then, which are attached to the engine is the driving-wheel, and forms the special means of locomotion, while the other cogged-wheels of course merely revolve without exercising any traction. But immediately a halt is required, all these wheels become of equal importance, and supply a prompt and most efficient brake, since directly they are locked, the train is brought to a stand-still, and held as in a vice even on the steepest inclines. Other brake-power is also applied; but this would seem to be the efficient means of control in case of accident.
It will be seen, therefore, that the danger of the train running away is carefully provided against; and no less care has been bestowed on the means for preventing the train leaving the rails, a danger fully as alarming as the other on a line which, for the greater part of its course, runs on the brink of a fearful precipice. Along each side of the central or rack rail, which is raised some inches from the ground, runs a projecting edge; and the engine and carriage are provided with two strong rods, the ends of which are bent in such a manner as to pass under these projections. Any jerk or jump of the train, therefore, would be resisted by the pressure of these bent ends against the under surface of the projections.