ART. V.-1. Traforo delle Alpi tra Bardonnèche e Modane: Relazione della Direzione Tecnica alla Direzione Generale delle Strade Ferrate dello Stato. Torino: 1863. 2. Rapport adressé à la Compagnie des Chemins de Fer du Nord de l'Espagne sur les Travaux de Percement du Mont Cenis. Par M. NOBLEMAINE. Neuilly: 1861. 3. Notice Historique sur la Percée du Mont Cenis et les Nouvelles age, prolific in triumphs of engineering skill, has produced, there is none which--whether we regard the difficulty of the undertaking or the importance of the object-more conspicuously challenges attention and deserves admiration than the great tunnel through the Alps, now steadily advancing, of which we propose, in the following article, to give a short account. Το Although the most frequented in modern times, the Mont Cenis is by no means the oldest of the passes of the Alps. It seems not to have been known to the ancient Romans, nor to have been used as a highway, or at all events not as a military road, until the middle ages. Recent researches have established the fact, almost beyond a doubt, that Hannibal led his army into Italy by the pass of the Little St. Bernard. reach the north of Italy and the plains of Lombardy from France, however, the shortest route is by way of Chambéry and the valley of the Arc. The railway, which leaves the Paris and Lyons line at Ambérieux and passes by Culoz and Chambéry, has been pushed forward to St. Michel in that valley, and from this point the traveller proceeds in a diligence as far as the village of Lans-le-bourg-a distance of about sixteen miles-where the ascent of the Mont Cenis begins. About onefourth of the distance between St. Michel and Lans-le-bourg, in a romantic part of the deep valley through which the rapid torrent of the Arc forces its way-shut in by lofty snowcovered mountains-lies the poor little hamlet of Fourneaux, and about a mile beyond it the larger but still insignificant village of Modane. On the right of the road, close to Fourneaux, the attention of the traveller is arrested by numerous white buildings which have the appearance of barracks; behind them a steep inclined plane, with two lines of iron tramway, ascends to a considerable height, and stops at two square-framed doors placed against the side of the mountain, near which are perched a few cottages and workshops. On the same line with the top of the incline, and a few paces to the east or right, may be distinguished a semicircular hole, out of which the spectator may perhaps, at the moment when he gazes, see a waggon or waggons issuing loaded with broken stones, and tilting their contents down the steep side of the mountain. Those buildings are the dwellings and workshops of the men employed in piercing the Alps, and that hole is the mouth of the great tunnel itself on the Savoy or northern side. Hopeless indeed must have appeared even a few years ago the idea of carrying a railway through the mighty barrier with which Nature has girdled Italy, and which, while it has too often failed as a defence against invasion, has had the effect of isolating her in a great degree from the rest of Europe, and has impeded her material prosperity. The genius of Napoleon did much when under his auspices the Simplon road was made, and the traveller could climb the lofty summit of the Alps comfortably seated in his carriage. M. Céard of Geneva, to whom that noble work is due, the more remarkable as it was the first of its kind, relates in his account of it that the Emperor Napoleon frequently summoned him to his presence to ask the same question: "Eh bien! le canon, quand 'passera-t-il le Simplon? This was followed by similar roads across the St. Gothard, the Splugen, and the Stelvio; and when these magnificent roads were completed, it seemed as if all had been done that engineering skill could accomplish to make a highway into Italy. Nor is it likely that more would have been attempted if steam had not entirely changed the nature of the case. The delay occasioned on a long journey by the ascent and descent of these mountain-passes was little felt when the greatest rate of speed on level roads did not exceed eight or nine miles an hour. But when railways began to spread their multitudinous arms on both sides of the Alps -when they crept up the valleys, and the course of the locomotive was suddenly arrested by the frowning masses of rock which seemed to say, Thus far shalt thou come and no 'farther-when the traveller had to exchange the luxurious saloon in which he was whirled along like an arrow through the air for the uncomfortable seat of a slow and jolting diligence the question irresistibly occurred, Is it possible for a locomotive to scale that lofty wall? or, if not, is it impos'sible to carry on the railway through the Alps?' The Austrian engineers, who have shown the greatest boldness and skill in the construction of Alpine roads, were the first to deal with this difficult problem. The railroad from Vienna to Trieste 6 crosses the Noric chain of the Alps at Semmering. The line ascends in gradients varying from 1 in 40 to 1 in 100 for 25 miles from Gloggnitz station to the summit of the pass, and then crosses the watershed in a tunnel 4,000 yards in length at an elevation of 2,893 English feet above the sea. This colossal work was accomplished for the Austrian Government by the engineer Carlo Chega, between 1848 and 1854. Another line of railway is also far advanced across the Brenner, between Botzen and Inspruck, which will open a very easy and direct mode of communication between central Europe and Northern Italy. But the Italian Government was naturally anxious that these important Alpine passes for steamcarriages should not be exclusively in the hands of Austria; and they therefore applied themselves with great energy to open a similar connexion between the Italian kingdom and the French provinces both of Savoy and of Nice. At first the favourite idea was that a practicable railway could be so constructed as to climb the mountain, and many were the ingenious schemes devised for the purpose. Perhaps in nothing has engineering science made more rapid progress than in the power of overcoming steep gradients. We well remember when the man would have been thought a visionary who should have proposed to make a locomotive line with a gradient of one in fifty; even one in a hundred was thought a formidable obstacle. Now, however, gradients are faced of one in thirty, or even one in twenty-seven, of which an example exists in England, and a ruling gradient of one in fifty is only considered objectionable, inasmuch as it limits the carrying power of the engine, and so increases the ratio of the working expenses to the gross returns. It is, in fact, a mere question of expense. But the gradient of the Alps! That was a gradient which transcended all experience. Still, engineers did not despair. The possibility of a railway across the Simplon was seriously discussed, and we believe that the late lamented Mr. Robert Stephenson was employed by a company to survey the pass, but his report was unfavourable. We remember, ten years ago, meeting in a small chalet near the summit of the mountain a foreign gentleman surrounded by maps, and plans, and sections, who told us that he was bent upon the same errand. Stationary engines, cog-wheels, pneumatic tubes-every kind of mechanical apparatus, were proposed to meet the difficulty, but hitherto without result.* * An experimental line is at this moment in operation on the Mont Cenis, on the plan invented by Mr. Fell, an American, for A tunnel was thought of and talked of, but it seemed the dream of enthusiasts. The difficulties in the way were indeed tremendous, and might well appal the boldest engineer. In the first place, the length would be much greater than had ever been before attempted, and how was a sufficient quantity of air to be obtained in the gloomy heart of the mountain to enable the passengers to avoid suffocation? How, in the progress of the excavation, were the workmen to breathe? At the distance of miles in the interior what might not be found? Perhaps some yawning chasm and dark unfathomable abyssor, still worse, some subterranean lake which, bursting through the aperture, would drown the workmen and sweep in a resistless torrent through the gallery. The materials of the rock might be harder than granite or the hardest whinstone yet encountered, which so often in Scotland has tired the patience and exhausted the purse of the contractor. To put down bores, the ordinary mode of ascertaining the nature of the ground to be excavated, was of course out of the question, and the imagination ran riot as it depicted the character of the unknown region of the interior. The quickest and cheapest mode of making ordinary tunnels is by sinking vertical shafts at intervals from the summit, but this would be plainly impossible in the Alps. It has been calculated that it would take forty years to make one of these shafts so as to strike the line of the axis of the Alpine tunnel; and if, owing to the almost insuperable difficulty of sinking a vertical one, it were made oblique, it would be as long as the actual tunnel itself. The gallery, the application of steam traction to ordinary carriage roads across mountains. The spot selected for the trial is on the zigzag road that ascends the mountain on the Savoy side, and the line is two miles and a quarter in length. The inclines vary from 1 in 23 to 1 in 12, and the smallest radius of the curves is one-fifth of a furlong. There are three sets of rails, of which the middle one is placed on an elevation, and it is used to secure the adhesion of four horizontal wheels attached two to each side of the locomotive. The lower rim of each of these wheels has a catch that firmly clasps the middle rail, so as to prevent the engine from being thrown off the line. They have also a lateral movement which acts as a powerful break and enables the train to be almost instantaneously stopped, even when going at full speed. It is calculated that by means of this system, when completed, the distance between St. Michel and Susa could be traversed in four hours and a half. We saw the locomotive at work a few months ago, and the effect at a distance was very curious. It seemed with its train like an avalanche descending the mountain, and the illusion was increased by the long line of steam which floated above the snow and was hardly distinguishable from it. therefore, must be excavated by horizontal cutting from end to end, although, of course, the cutting might begin at each extremity at the same time, and go on simultaneously until the two sections met half-way in the middle of the mountain. But here a fresh difficulty occurred. Suppose that the lines did not meet? It is obvious that, unless the axis of each half of the tunnel was mathematically in the same straight line, the result would be either that the one line would cross the other at an angle impracticable for a locomotive, or that they would be in parallel lines and so miss each other, causing thus the expense to be incurred of two tunnels instead of one. In fact, a more serious mistake would be committed than that which is said to have happened in Ireland, where a line of railway was begun at the two ends with different gauges, and it was not until each half of the work was completed that it was discovered that the one would not fit into the other. Notwithstanding, however, all objections and all obstacles, the minds of thinking men were haunted with the idea of the practicability of a tunnel, and it was even made the subject of poetry. In 1851 the Academy of Sciences in Savoy offered a prize for the best poem on la Percée du Mont Cenis, and the successful competitor was a lady, Mdlle. Chevron, of Barberaz, of whose verses, however, we are not able to speak in very high terms. She represents the Mont Cenis as angry at the affront it was about to suffer at the hands of unromantic engineers: 'Le Mont Cenis pourtant lève un front courroucé, And the injured mountain exclaims : Et l'on viendrait tenter de me réduire en poudre, Quand depuis six mille ans je résiste à la foudre.' Happily, however, as we shall see, Mont Cenis has been spared this humiliation. The first question was to determine the spot which presented the conditions most favourable for the solution of the problem. These obviously were: 1, the least thickness in the intervening barrier, or, in other words, the shortest passage through the mountains; 2, the most penetrable kind of rock; and 3, the most convenient points on each side for connecting the tunnel with the existing railways in Savoy and Piedmont. honour of first hitting upon the exact place on the Italian side which subsequent researches have confirmed as that which is most suitable for the line of the tunnel is due to an inhabitant of the village of Bardonnèche in the valley of Rochemolles, The |