The “Daily News” of January 22nd, 1875, in presenting its readers with a chart of the proposed tunnel, offered also the following sensible and interesting comment on the subject:

“This long-debated project has at length emerged from the region of speculation, and is entering the stage of practical experiment. On this side the Channel a company has been formed to carry out the work, and on the other side the French Minister of Public Works has presented to the Assembly a Bill authorizing a French company to co-operate with the English engineers. The enterprise is one worthy of the nations which have in the present generation joined the two shores of the Atlantic by an electric cable, and cut a ship canal through the Isthmus of Suez, and of the age which has obliterated the old barrier of the Alps. All these gigantic undertakings seemed almost as bold in conception and as difficult of execution as the great work now about to commence. Those twenty miles of sea have long been crossed by telegraph lines; they will soon be bridged, as it were, by splendid steamers; but even our own generation, accustomed as it is to gigantic engineering works, has scarcely regarded the construction of a railway underneath the waves as within the reach of possibility. M. Thomé de Gamond, who first made the suggestion five and thirty years ago, was long regarded as an over-sanguine person, who did not recognize the inevitable limits of human skill and power. A tunnel under twenty miles of stormy sea seemed very much like an engineer’s dream, and it is only within the last few years that it has been regarded as a feasible project. Of its possibility, however, there seems now to be no manner of doubt. It is merely a stream of sea-water, and not a fissure in the earth, which divides us from the Continent. Prince Metternich was right in speaking of it as a ditch. The depth is nowhere greater than one hundred and eighty feet; and so far as careful soundings can ascertain the condition of the soil underneath the water, it consists of a smooth unbroken bed of chalk. The success of the experiment depends on this bed of chalk being continuous and whole. Should any very deep fissure exist, which is extremely improbable, the tunnel may probably not be driven through it. But given, what every indication shows to exist, a homogeneous chalk bed some hundreds of feet in thickness, the driving of a huge bore for twenty miles through it is a mere question of time, money, and organization, and as the engineers have these resources at their command, they are sanguine, and we may even say confident, of success.

“The method by which it is proposed that the excavation shall be made is in some respects similar to that which was successfully employed in tunnelling the Alps. Mont Cenis was pierced by machinery adapted to the cutting of hard rock; the chalk strata under the Channel are to be bored by an engine, invented by Mr. Dickenson Brunton, which works in the comparatively soft strata like a carpenter’s auger. A beginning will be made simultaneously on both sides of the Channel, and the effort will at first be limited to what we may describe as making a clear hole through from end to end. This small bore, or driftway as it is called, will be some seven or nine feet in diameter. If such a communication can be successfully made, the enlargement will be comparatively easy. Mr. Brunton’s machine is said to cut through the chalk at the rate of a yard an hour. We believe that those which were used in the Mont Cenis Tunnel cut less than a yard a day of the hard rock of the mountain. Two years, therefore, ought to be sufficient to allow the workers from one end to shake hands with those from the other side. The enlargement of the driftway into the completed tunnel would take four years’ more labour and as many millions of money. The millions, however, will easily be raised if the driftway is made, since the victory will be won as soon as the two headways meet under the sea. One of the great difficulties of the work is shared with the Mont Cenis Tunnel, the other is peculiar to the present undertaking. The Alps above the one, and the sea above the other, necessarily prevent the use of shafts. The work must be carried on from each end; and all the débris excavated must be brought back the whole length of the boring, and all the air to be breathed by the workmen must be forced in. The provision of a fit atmosphere is a mere matter of detail. In the great Italian tunnel the machines were moved by compressed air, which, being liberated when it had done its work, supplied the lungs of the workers with fresh oxygen. The Alpine engineers, however, started from the level of the earth: the main difficulty of the Submarine Tunnel seems to be that it must have as its starting-point at each end the bottom of a huge well more than a hundred yards in depth. The Thames Tunnel, it will be remembered, was approached, in the days when it was a show place, by a similar shaft, though of comparatively insignificant depth. This enterprise may indeed be said to bear something like the relation to the engineering and mechanical skill of the present day which Brunel’s great undertaking bore to the powers of an age which looked on the Thames Tunnel as the eighth wonder of the world. Probably the danger which will be incurred in realizing the larger scheme is less than that which Brunel’s workmen faced.

“It is, of course, impossible for any estimate to be formed of the risks of this enormous work. They have been reduced to a minimum by the mechanical appliances now at our disposal, but they are necessarily considerable. The tunnel is to run, as we understand, in the lower chalk, and there will be, as M. de Lesseps told the French Academy, some fifty yards of soil—a solid bed of chalk, it is hoped—between the sea-water and the crown of the arch. Moreover, an experimental half-mile is to be undertaken on each side before the work is finally begun; the engineers, in fact, will not start on the journey till they have made a fair trial of the way. Altogether the beginning seems to us to be about to be made with a combination of caution and boldness which deserves success, even though it should be unable to command it. Unforeseen difficulties may arise to thwart the plans, but the enterprise, so far, is full of promise. The opening of such a communication between this country and the Continent will be a pure gain to the commercial and social interests on both sides. It obliterates the Channel so far as it hinders direct communication, yet keeps it intact for all those advantages of severance from the political complications of the Continent, which no generation has more thoroughly appreciated than our own. The commercial advantages of the communication must necessarily be beyond all calculation. A link between the two chief capitals of Western Europe, which should annex our railway system to the whole of the railways of the Continent, would practically widen the world to pleasure and travel and every kind of enterprise. The 300,000 travellers who cross the Channel every year would probably become three millions if the sea were practically taken out of the way by a safe and quick communication under it. The journey to Paris would be very little more than that from London to Liverpool. It is, however, quite needless to enlarge on these advantages. The Channel Tunnel is the crowning enterprise of an age of vast engineering works. Its accomplishment is to be desired from every point of view, and, should it be successful, it will be as beneficent in its results as the other great triumphs of the science of our time.”

The Channel Tunnel is not yet a fait accompli, although the preliminary trial works have been made at both ends. Drift-ways of some ten feet diameter have been cut beneath the waters of the strait, and instead of the experimental half mile mentioned in the foregoing paragraph, the works have been pushed forward on the English side for about a mile and a quarter with complete success. As was anticipated, no physical difficulties were met with, for the machines did their work with the greatest ease, and the drift has now remained for some years practically free from any infiltration of water. These results indicate that the scheme might be completed with speed and safety. Parliament, however, has refused to allow the undertaking to proceed, being moved to this course by the opinions of military authorities, who see dangers to England in the completion of this enterprise, or at least such a disturbance of the British complacency at the notion that our island might be reached otherwise than “by the inviolate sea,” that the whole land would be liable to terrors and alarms from invasion by stratagem. It is represented that huge fortresses and a special army for that purpose would become necessary to guard the mouth of the tunnel were it made. This is, perhaps, the kind of objection which such an enterprise could not fail to raise. But it can hardly be expected that all the commercial and international advantages which the realization of the scheme would undoubtedly secure are for ever to stand in abeyance for such opinions as have, for the present, caused the operations to be suspended. It has been pointed out that there are many ways of instantly rendering such a tunnel impracticable in case of a sudden alarm. But the necessity could only arise after a supposed paralysis or destruction of such army and navy as Britain could bring together to defend her land. Perhaps military skill will presently devise less costly methods of defence than those authorities now suppose the tunnel would require; or, even if such armaments were really necessary for our sense of insular security, the expense might be no unprofitable outlay for the advantages to be gained. It is satisfactory to know that the promoters of the scheme are sanguine of the subsidence of the military and political prejudices, which are now the only obstacles to its accomplishment. A somewhat unexpected result from the operations in connection with the experimental driftways has been the discovery, on the Kentish coast, of seams of coal underlying the chalk at a workable depth.

THE ST. GOTHARD RAILWAY.

Since the completion of the Mont Cenis Tunnel, a still greater piece of rock boring has been begun and finished in the great tunnel of the St. Gothard Railway. The construction of a railway to connect Italy with Switzerland, was a project conceived as far back as 1838, when the first railway company in the latter country was constructed. The route of the proposed line was a matter of much debate, not alone on account of difference of engineering opinions, but also by reason of the various competing interests that would have to be reconciled and induced to co-operate in the work. The St. Gothard route was only one of the several schemes that were advocated, and the first decisive step appears to have been taken at Lucerne, where, in 1853, a meeting was called by the authorities of the canton to consider the merits of the project; the result being that the Lucerne Government addressed to the Federal Council a representation of the advantages this route would afford. More discussion ensued, and it was only when Switzerland appeared likely to have no share in the traffic between the Milan district and the more northern parts of Europe that, in 1861, the partizans of the St. Gothard route appointed a provisional committee to take action in the matter. This committee had plans prepared, and sent a deputation to obtain the assent of the Italian Government. The canton of Tessin, through which the projected line, or its then surviving rival, was designed to pass, became a lively scene in the game of speculation, for promoters rushed in to secure, if possible, concessions which they might sell at a very advanced price to the winning party. For this purpose came to that poor Swiss canton Jews and Christians from every land. The St. Gothard route gained the day, and a Union was, in 1863, formed by the concurrence of the two principal Swiss railways and fifteen of the cantons most interested in the scheme. Difficulties and delays were, however, encountered before the necessary compacts could be concluded with the neighbouring states—and then there came the war of 1867. So that it was not until the latter part of 1872 that the construction of the line was actually entered upon. Before the great work of piercing the St. Gothard had been completed, the undertaking was embarrassed by financial difficulties arising from the fact of the lines on the Italian side costing more than double the estimated amount. The Swiss Government, however, voted a special subsidy, and the work, which had been suspended for a while, was proceeded with; much attention being paid to its economical prosecution. In 1881, when the line was opened, the mails were carried between Zurich and Bellinzona in seven hours, instead of in thirty hours as previously required for transit by the excellently appointed mail carriages under the Federal Administration.

Besides the great tunnel, the St. Gothard line has some unique devices in railway construction which cannot fail to interest the reader. Several of the passes over the Alps have been made use of from time immemorial. We know that Hannibal led his Carthaginian hosts over one of them, and that they have been traversed by Roman legions, as well as by Germanic hordes. But, although the St. Gothard is the most direct of all the routes, it never afforded a passage to armies or migratory tribes. The road through this pass was not formed by the use of any elaborate appliances for overcoming the natural obstacles: it was rather the work of simple peasants and mountain shepherds, with such rough constructions in wood as might give a sufficiently secure passage across the torrents and gorges. The old road keeps beside the Reuss from the head of the lake of Lucerne until it reaches the highest level of the pass, where the water-shed occurs. It then descends steeply, with many twists and windings, to the banks of the Ticino, and it follows the course of this river to its embouchure at Tresa, on Lago Maggiore. The railway follows the same course, except that it cuts off the higher part of the pass by the great tunnel piercing the mountain. The scenery throughout could, perhaps, be nowhere equalled for the variety of its wild grandeur.

The great tunnel of the St. Gothard passes from Gœschenen, on the Reuss, beneath the col of the pass, and emerges close to the village of Airolo, on the banks of the Ticino. The length of this tunnel is rather more than nine and a quarter miles, so that it is about one and a half miles longer than the Mont Cenis Tunnel. Its northern end is 3,638 feet above the sea level; its southern end is higher, namely, 3,756 feet; but there is an intermediate point in the tunnel higher than either-–3,786 feet—and from this there is a uniform incline in each direction. The tunnel is 300 yards beneath the lowest part of the valley of Andermatt, and the summits of the mountains it traverses are at least a mile above it. The motive power by which the rock-drilling machines used in driving the tunnel were actuated was, as in the case of the Mont Cenis Tunnel, compressed air; and the power used for compressing the air was, in this case also, a head of water,—but this was not applied in the same way. The waters of the Reuss at the northern side, and those of the Tremola and of the Ticino at the southern side, were taken at a considerable height in very large cast-iron pipes, and were made to act upon powerful turbines that gave motion to the compressing machines. These were capable of compressing the air so that its volume was reduced to one-twentieth, and the pressure it then exercised would, of course, be equal to that of twenty atmospheres, or about 300 lbs. on the square inch,—or more than three times as much as was made use of in the Mont Cenis Tunnel. The compressed air, carried through pipes to the head of the workings in the rock, was there allowed to exert its force on the pistons of the perforators in the manner already described. There was, in fact, a continual repetition of exactly the same cycle of operations of boring, charging, firing, etc., that are mentioned on page 355. A large quantity of the compressed air was always allowed to rush into the work immediately after each blasting, in order that the smoke and other products might be driven out and the atmosphere rendered fit for respiration. In attacking the mountain simultaneously from each side it was, of course, essential that the tunnels should be driven in precisely the same direction, and therefore the positions of the points of departure had to be determined by very careful surveys. At Gœschenen, the gorge of the Reuss did not naturally admit of a sufficient distance of vision to fix the direction with the required accuracy, and it became necessary to pierce a thick mass of rock with a special tunnel for the purpose of taking a sight sufficiently far back. At Airolo, again, the tunnel had to enter the valley by curving towards the village; and here a provisional gallery had to be driven in the straight line.

Several contractors competed for the work of constructing this great tunnel, and it was at first supposed that an Italian company, which was managed by some of the principal engineers engaged on the Mont Cenis, would be almost certain to obtain the contract. The promoters, however, intrusted the work to a private individual, M. Louis Favre, of Geneva. This gentleman undertook to complete the tunnel in eight years, at the price of 2,800 francs per mètre for the work of excavation merely, exclusive of masonry, etc. This cost would be not far from £101 per English yard. The contract was signed on August 7th, 1872, and on September 12th of the same year M. Favre commenced operations at the southern end, and the work at the northern end was begun on October 9th following. The operations were carried on with great energy, and even during the period of the Company’s financial difficulties there was no stoppage of the works between Gœschenen and Airolo. It has been suggested that it was largely due to the regular and successful progress of this great piece of rock boring that the Company were enabled to re-establish themselves on a basis that ensured the completion of the whole undertaking. The contractor, on his part, did not fail to encounter many physical difficulties. At the southern end much trouble was caused by torrents of water gushing from the soil, many of these being of great volume and force; in fact, the work was here carried on for nearly a whole year in the midst of water—for the ground for the first mile consisted of glacial and other deposits, which were intersected by subterranean water-courses. Reaching the solid rock was here a relief. But at Gœschenen little of loose formation was met with; but the rock encountered was of extreme hardness—consisting, indeed, of almost pure quartz, which had the effect of quickly blunting the points of even the best tempered tools. But another kind of difficulty had to be overcome when the workings got beneath the vale of Urseren. Here, at several places, layers of argillaceous matter were found between the masses of hard rock. These layers were easy enough to pierce through, but on account of the pressure of the rocks in which they were interspersed, they were squeezed out and gradually protruded within the tunnel, which would soon have become entirely obstructed. At first a very massive lining of timber was tried, but it was soon found that this must be replaced by a solid vaulting of stone. The first vault failed to sustain the pressure, and so did the second, although the thickness of the material was more than a yard. In some places these operations had to be several times repeated, and from this cause the cost of parts of the tunnel has been nearly £1,000 per yard.

The instances above mentioned may be taken as mere specimens of the physical difficulties attending a work of this kind. There are often others arising from the unusual circumstances under which the workmen are placed, and others again from accidental causes alone. M. Favre experienced some of these, as, for example, when one year a fire destroyed the greater part of the village of Airolo; another year there was a strike on the part of the workmen. The high temperature in the workings was, especially towards the end, a source of great trouble. The cause of the heat is no doubt the same as that which is held to support the theory of the earth’s central heat. Numberless observations have established the fact that the temperature of the earth’s crust increases as we go deeper. The increase appears not to be uniform in different places—at least there is much discrepancy in the estimates that have been made. But as a sufficient approximation to a general statement, it may be taken as proved that for every seventy feet or so that you go below the surface of the ground, there is an increase of the temperature of the strata equal to 1° Fahrenheit. Now, the workmen in the two sections of the tunnel had, at last, to carry on their labour in a temperature of more than 100° Fahrenheit. This, perhaps, might have been one cause of some unprecedented kinds of malady that appeared amongst the tunnel labourers. M. Favre himself was not destined to witness the completion of his great undertaking, for, on July 19th, 1879, as he was returning from an inspection of the tunnel, he fell into the arms of his companions, struck down by a fatal attack of apoplexy. On February 29th, 1880, the last fuse required to blast down the rock separating the two tunnels was fired by one of the few workmen who had been engaged in the operations during the whole period from their commencement. It was found that the two tunnels met exactly and coincided in direction.

The construction of such a line of railway as the St. Gothard tries the skill of the engineer, and taxes all the resources of his art. The problems presented by the nature of the route, and the requirements of the iron road, have in this case been successfully solved by bold expedients—by new and ingenious devices. The reader will readily understand that the ordinary cart road may wander about, so to speak, of its own will; it is not confined to the limited gradient of the line; or obliged to make its turns and curves of at least a certain radius. Now, there are portions of the valley where the general slope is too steep for the railway to follow, and where it was necessary to form it in zig-zags, so that certain sections of the gorge or valley may be several times traversed by the line returning upon itself. Fig. 187d is a view showing an incident of this kind, and one of the most interesting spots on the route. The dark line on the spectator’s right is the track of the railway; the white trace, which in the lower part of the view is seen on the other side of the Reuss, is the ordinary road. If this last be followed up the valley, it will be seen to cross first the Reuss, and then a tributary stream (the Maïenreuss) descending through a gorge on the right, after which it zig-zags up a hill to the village of Wasen (the church of which village is seen crowning the eminence in the centre of our view), and then it continues its course up the valley, passing through a small village, and disappearing over the shoulder of a hill on the right bank of the river. Let us now carefully follow the railway from where the train at the bottom of the picture is seen ascending the gradient. The line presently passes under a bridge, and then enters the tunnel, near to the entrance of which a small building will be noticed. The course of the tunnel is shown by the curve marked in dots, for this tunnel makes a round within the rock, and the railway emerges to day again at a point lower down in the course of the valley than at the entrance to the tunnel, but at a higher level. It is seen in the figure appearing from behind the rocks in the right-hand lower corner, passing under a short tunnel and continuing along the mountain side. The curved tunnel resembles in direction part of the turn of a corkscrew; it is one of a series of helicoidal tunnels of which there are several examples on the line. The entrance to this tunnel is 2,539 feet, the exit 2,654 feet, above the sea level. It is known as Pfaffensprung (Monk’s Leap) Tunnel. The line again enters a short tunnel, and immediately crosses the deep gorge of the Maïenreuss, to plunge again into another tunnel at the base of this hill on which Wasen stands. Higher up it crosses the Reuss and enters the helicoidal tunnel of Wattingen (dotted line). On emerging from this, the line re-crosses the Reuss, and may now be traced down the valley, but higher up on the mountain side, coming in the reverse direction, and after passing Wasen on the other side, re-crossing the Maïenreuss gorge by a second bridge. Then turning back again through another helicoidal tunnel (Leggistein) the line crosses the Maïenreuss for the third time, and continues its course up the valley. Fig. 187c gives us a near view of Wasen, and a glimpse up the gorge of the Maïenreuss from its junction with the Reuss. The bridge with the large single arch is that which carries the ordinary road, and higher up we see the three iron bridges that carry the railway backwards and forwards in its doublings. We can well imagine the perplexity of anyone ascending the valley in the train for the first time, and ignorant of the peculiarities of this extraordinary railway. In crossing the first, or lowest bridge, over the Maïenreuss, he would catch a glimpse of the church of Wasen, perched on its hill, high above him, and on his right. After being carried through more tunnels, and over more bridges, he would some minutes afterwards be disposed to think that his eyes were deceiving him, for there, still on his right, he would see the same church, but now on about the same level as the train. Again, after more tunnels and bridges, the church would once more appear, transferred to the left of the line, and sunk very far down. These several apparitions of the same building in different positions, after the train has seemed to have been pursuing its onward course the while,—which course would not be judged by any impressions the traveller would usually receive to be other than rectilinear,—are indeed a regular bewilderment to the inexperienced traveller. He is then obliged finally to resign himself passively to be carried he knows not whither or how, for his sense of direction is completely at fault;—the train comes out of tunnels which seem turned the wrong way; the river, which he expected to find on the left hand, he sees on the right; and the Reuss appears to have reversed the direction of its flow.

It is understood that the St. Gothard line has been a great commercial success, for the number of passengers entering and leaving Italy by that route has been enormous, and still shows a large annual increase. Indeed, the prosperity of the line has been so great that the project has been revived of carrying another railway over the Alps to connect Italy and Switzerland by way of the Simplon. If this scheme should be carried out, the mountains will be pierced by a tunnel of a length double that of the St. Gothard.