We have drawn a straight line between Lanslebourg and Susa, solely for representing the general direction of the road; but in reality the road is a cork-screw with fully as constant deviation from the straight line as is exhibited by that useful article of domestic economy, and perhaps we could not find a better manner of illustrating the difference between an ordinary road on the level, and one on or through a mountain passway. If the iron of a cork-screw went straight from where it is fastened to the handle, to its point or extremity, it would measure about three inches, but its convolutions extend it to ten. It is precisely the same with the road between Lanslebourg and Susa. If it were on the plain it would measure about seven miles; but its convolutions, its twists and its turns, its zig-zags, and its lacets convert seven into twenty-five. The length of the tunnel when completed will be 12,220 metres, or 7½ English miles and 242 yards. It consequently exceeds by about 4½ miles, the next longest railway tunnel on the continent of Europe, that of Lanerthe, on the Paris, Lyons and Mediterranean Railway already referred to.

The Tunnel of the Alps has a double nationality, it is half, exactly half, French, and exactly half Italian. By the convention of 1856, between the Governments of Sardinia and France, 6,110 metres of perforation and of lining were to be made at the expense of each country, but the whole of the works were to be done by Italy exclusively. They were commenced on each side of the mountain in 1857. For the first 3½ years, that is, until the end of 1860, the process of perforation was performed by manual labour only; in 1861 and 1862 it was partly by manual labour and partly by machinery; since 1862, machinery has been exclusively adopted.

The following Table sets forth the progress made on each side since the commencement of the work.

THE TUNNEL OF THE ALPS.

The rate of progress given in the foregoing Table is very different from what was expected previous to the commencement of the works. It was then anticipated that the tunnel would be excavated from end to end before the close of 1864, but it was not until the 15th of October, 1866, or 9¼ years after operations had been begun, that exactly one-half was perforated. On the 1st November, 1867, the half had been exceeded by 1,958 metres, still leaving 4,152 metres to be excavated. The amount of perforation accomplished on the two sides of the mountain has always been unequal, for of the 4,152 metres yet to be excavated, 2,905, equal to about 1? mile, have to be accomplished on the French side, whilst on the Italian there are two-thirds of a mile. This will be understood by an explanation of the strata through which the tunnel is to be carried. Commencing at Modane, there are 2,140 metres of schist, then 363 of quartz, followed by 2,706 of compact limestone, and finally 901 of schist. This completes one half; the other, or Italian half, is all schist. The only rock comparatively easy in working is the schist, but from the commencement the schist on the French side was of a more resisting character than that on the Italian. The miners came upon the quartz exactly where they expected to find it, but instead of its being a stratum 400 metres thick, as was anticipated, it turned out to be only 363 metres; nevertheless, it required two years, less two months, to bring it into subjection, that is, from the 15th of June, 1865, until the 20th of April, 1867,—the progress forward during all that time, not much exceeding half a metre (about 20 inches) a-day. The compact limestone nearest to the quartz having been partly decomposed by the action of this latter, was very workable. Hence, during May and part of June 1867, the advance was very considerable, but since June the compact limestone has proved to be harder but not so difficult to work upon as the quartz. For six weeks the engineers were hopeful that they could go on at the rate of three metres a-day. If such progress could have been unflinchingly maintained, the excavation on the French side could have been accomplished by August 1870. With two metres a-day it will require until March 1872; but if, the advance do not exceed a metre and a-half a-day for two-thirds of the whole distance, the tunnel cannot be perforated under six years, which brings the date to July, 1873.

But the perforation of the rock is not the only serious impediment to progress. All things that live and breathe, miners among the number, require air for their sustenance; and, in order to supply it in sufficient quantities for the support of the human moles within the interior of the tunnel, it has been necessary to resort to special appliances for this purpose. Immense machinery, moved by water-power of an aggregate force for each end of about 400 horses, erected at both entrances of the tunnel, works not only the boring machines, but, at the same time, furnishes the miners with the necessary ventilation. The air is compressed to five atmospheres by means of the water-power just referred to; and the double application of the air is the ingenious contrivance of Messrs. Someilier, Grandis and Grattoni, the distinguished Italian engineers, under whom the works are conducted. Until recently the ventilation, although indifferent except at the site of the boring machines, was excellent in their vicinity; but with each metre that the works progress farther into the mountain, the difficulties of ventilation are added to; especially so on the French side, and for a reason that will at once, on a moment’s explanation, be evident to the reader. When the boring machines have made the usual holes in the rock about three feet deep, they are filled with gunpowder, and exploded. Now, if the excavation of the mountain had been made partly by adit and partly by shaft, as soon as one of the latter had been made, the smoke from each explosion beyond it would have found vent through it to the outer air, and in a few minutes the forward face of the tunnel would be ready for the fresh action of the boring machines. But as there is no shaft in the Cenis Tunnel, the whole of the smoke created by each explosion has only one means of exit—that is, through the tunnel’s mouth. Smoke, in its escape, wants to ascend (as we know by our everyday experience), but it cannot do so for the want of a shaft; it cannot get out even on the level, for the gradient in the tunnel on the French side is, on an average, 1 in 45, or 117 feet 4 inches per mile. As the perforation had, on the 1st November last, been accomplished to the extent of 3,205 metres, the face of the tunnel was about 226 feet higher than the entrance,—consequently, the smoke of each explosion at the present time is not only not able to come out on the level, but it has actually to descend the number of feet just stated before it can commingle with the outer air; and the number of these feet of elevation wall continually increase, until, at the end of the French perforation, there will be 429. We believe it is a matter of fact, that the ventilation is every day becoming worse, and the means of supplying the requisite air are becoming more difficult with each metre of advance made, and so it must continue until the final perforation has been (for no doubt it will be) accomplished.[138] On the Italian half, the rock is throughout, schist, and the gradient, being only one in 2,000, or 2-8/25 per mile, all the elements for progress will continue to be, comparatively, as favourable as they have hitherto been; and even with a much less rapid rate of advance than on the French side, it requires no great gift of prophesy to “forecaste” that the boring machines from Italy will be ready to embrace those from France long before the latter shall have arrived at the midway point. But let it be understood that the works from the Italian side cannot go on a yard beyond midway,—first, on account of the gradient, which would dam up all the water percolating into the tunnel; second, because it would be impossible to keep the line of the tunnel, owing to the absence of all the external landmarks required for ensuring its correct direction. The embrace we have just referred to will take place 4,138 feet above the level of the sea, 1,645 above the level of St. Michel, 429 above the Modane entrance of the tunnel, but only 2-8/25 above that at Bardoneche, 2,360 above the level of Susa, about 5,360 feet below the highest point of the Great Vallon Mountain, and 2,520 feet below the summit of the Mont Cenis Railway.

What might have proved a source of great trouble and expense—water—has fortunately not as yet on any one occasion presented itself in a manner to cause alarm or even uneasiness. We need not therefore refer to this subject in any detail, but before proceeding to as important an element as any with which the tunnel is encompassed—cost—we had better state that the arch of the tunnel is a semicircle 25 feet 3½ inches at its base, 26 feet 3 at its broadest part, and 24 feet 7 inches high. (See diagram.)

Captain Tyler in his report of 1866, sets down the total cost of the tunnel and its 34½ miles of approaches at £5,400,000, or £128,500 per mile. Now we know that up to the present time each metre of tunnel excavated and lined (for it is to be lined throughout from stone quarried near to each entrance, with an occasional introduction of brickwork) costs 7,000 francs, or £280. This would bring its total cost exclusive of permanent way, which would be, say £30,000, to £3,421,600, but we believe that the farther the tunnel is penetrated, the expenses will increase rather in geometrical than arithmetical proportion, and that the average cost of the tunnel will not be 7,000 francs or £280 “per metre courant,” but 10,000 francs or £400. If this be so, the cost of the tunnel, without permanent way, would be £5,188,000. To this sum has to be added the cost of the 34½ miles of approaches. The nature and the probable cost of the works can be appreciated from the fact that they are now about to be let, and the contract time for their completion is to be four years and a-half from the date of their commencement. These 34½ miles of double railway cannot be estimated at less than £60,000 a mile or £2,070,000, making the total cost of the tunnel and of the railways which connect it with the railways of France to the north, and with those of Italy to the south, £7,258,000, or at the rate of £172,800 per mile. Possibly, if the construction were in the hands of a railway company instead of those of two governments, a saving of a million or so might be effected, but in any case the cost would be upwards of £6,000,000, or nearly £142,850 a mile.

In connection with the subject of cost, a calculation of Captain Tyler’s gives the following results. The difference, says the Captain, of elevation between the outer summit of the Mont Cenis Pass and the summit of the railway through the tunnel is 2,520 feet. The excess of working expenses in consequence of this difference of height, estimated on a traffic ten times as great as that which passed over the Mont Cenis in 1865, and the cost of traction per horse power and per hour being taken at 2¼d. (the cost on the Soemmering and the Giovi), an additional capital of £650,000, or £13,000 a mile, with interest taken at 6 per cent., is represented. If then £13,000 a mile be added to the £21,000 actual cost per mile of a permanent Alpine railway, the total cost of a railway on the mountain becomes, for the purposes of comparison, £34,000 a mile, as against whatever may be the cost per mile for the Tunnel Railway and its approaches. If they cost £142,850 a mile, the comparison will be as 31 to 142; but, if, as we believe, the cost will be £172,800, then the proportion will be at 31 to 172.

A few years ago people could think or speak of nothing else for the Alps but tunnels; there was to be a tunnel railway through the Simplon, one through the St. Gothard, and as immediately to the eastward of the Great St. Gothard range, there is a rapid diminution of elevation of the Alpine mountain, no less than three passes were named as suitable for tunnels, the special advantage of each being that they could be constructed by means both of shaft and of adit. These three passes commencing near Dissentis, run from north to south, and each, as it were, starting from one root, branches off and follows its own course through its own system of valleys, but the three unite in a common pass about two miles to the south of Olivione. They are called respectively the Cristillina (the easternmost), the Greina (the centre), and the Lukmanier (the westernmost). The length of tunnel suggested for the Cristillina was the most modest of all, only seven miles; for the Greina it was to be twelve and a-half miles, whilst that for the Luckmanier was proposed to be fifteen miles, nearly but not quite double that now constructing under the Great Vallon Mountain. But if the tunnel of the Lukmanier was to be the longest, its advocates were able to assert in its favour, that not only could the shafts be numerous, but that not one of them need be at a greater depth from the surface than two hundred yards. Well, notwithstanding these supposed advantages, these long tunnel railways have ever since remained a dead letter, and have long ago been consigned to rest in the wide laying burial ground of Utopia. We shall one of these days (probably, in four or five years) have one tunnel through the Alps; we are not likely in this or the succeeding generation to have a second.

At a very early period in the history of English Railways, the ventilation of tunnels came to be considered a very important question, and as usual on such occasions, ignorance furnished an immense number of facts and realities which experience showed to be nothing but fictions. It was in deference to the highly wrought popular feeling on the subject, when every manner of evil was prognosticated for travellers going through tunnels, that the late Mr. R. Stephenson was induced to construct the large ventilating shafts on both the Kilsby and the Watford tunnels of the London and North-Western Railway. There are two shafts in each of these tunnels, the diameter of each of the four being sixty feet. They may be said to divide the tunnels into three distinct parts, the periods of going along each space of sixty feet being perfectly appreciable by the traveller. The ventilation is no doubt better in consequence of the execution of these gigantic shafts; but experience has long since shown that shafts nine to twelve feet in the clear, are quite sufficient for all ventilating purposes, no matter how much the tunnel may be below the earth’s surface.

We are indebted to Mr. Charles S. Storrow, an American engineer of reputation, for a great deal of very interesting information upon the subject of the ventilation of tunnels, and the state of the atmosphere in them during and subsequent to the passage of trains. Mr. Storrow was sent to Europe in 1862, by the commissioners of the State of Massachusetts, which had been appointed by legislative action, in relation to the construction of the Great Hoosac tunnel already referred to. The tunnel first visited by Mr. Storrow, in England, was the Box Tunnel, of which in his report he furnishes a section. Its length is 3,227 yards; its gradient throughout is 1 in 100. It has five shafts, each being twenty-five feet in internal diameter. But this diameter is, as just stated, now considered to be unnecessary. The deepest shaft is 300 feet.[139] Mr. Storrow experienced no inconvenience as regards ventilation when going through the tunnel in passenger trains. On one occasion he proceeded through the tunnel in a hand car—“a passenger train passed us” says Mr. Storrow, “on the other track to that which we were on. It filled the tunnel with smoke and produced perfect darkness, so that the other ends of the tunnel (which had been seen most distinctly previous to the passage of the train) could not any longer be seen, and on removing the lights we were carrying, the person who sat at my side talking with me and touching me, was absolutely invisible. With all this, however, there was nothing troublesome to respiration. As we proceeded and successively passed the large shafts, a ray of light appeared directly under them, which, a moment afterwards was lost in intense darkness, and this continued until we reached the other end of the tunnel, after an interval of fifteen or twenty minutes from the passage of the express train.” Mr. Storrow was informed that “the ventilation of the tunnel depends a good deal on the weather. Whenever a strong clear wind blows, the smoke disappears very readily, but in fogs it is quite troublesome to the workmen. I could not find, however, that it seriously interfered with their work. Indeed there never was a time when it could not be done, if required. No artificial means had ever been used to ventilate the tunnel, but the passage of quick trains going through it in the ordinary course of the operations of the road, is a powerful agent for this purpose. With the steep grade of 1 in 100, the steam, on the descent of the tunnel, is nearly or quite shut off, and the train passes quickly through. The first engine which passed us, moving down the grade, produced no sensible effect upon the air, but in ascending the tunnel there is a very great expenditure of steam; the trains moving slowly, and heavy trains are assisted by a second engine. All this of course vitiates the air. The quick passage of a train always produces a current in the direction of its motion, and if made by a train running downward, and therefore using but little steam, its effect in clearing the tunnel is very marked. This effect is said, however, to be rather impeded than assisted by the presence of the shafts, and I found that the persons in charge of the tunnel, taking this circumstance, and the water admitted into the tunnel by the shafts, into consideration, would be pleased to have them closed altogether, and to depend for ventilation upon a natural current from end to end being caused by difference of temperature, or prevailing winds, and by the artificial current produced by the passage of quick trains.”

“Its most dangerous enemy is frost. In winter enormous icicles are sometimes formed by the gradual accretion, and if not removed would be very dangerous.”

Of the Sapperton tunnel on the Birmingham and Gloucester section of the Midland railway, 1,760 yards long,[140] Mr. Storrow says, “the grade is very steep, 1 in 70, or 75½ feet to the mile. Hence, in running up the tunnel a great deal of power is required, and an assistant locomotive is kept constantly in use. This, of course, creates a large additional development of smoke and steam, so that after the passage of a single heavy freight train up, the smoke would fill the tunnel for hours, and be quite offensive. Formerly coke was used on English railways, but latterly coal (which, as we know, produces a much greater volume of smoke) is now universally used. All agree that this change has been very injurious in tunnels. At the Sapperton tunnel the assistant engine is usually run down the tunnel immediately after the train has passed up, and thus assists in clearing away the smoke, but a quick passenger train running down the steep incline at great speed is found to be far more effectual, and is indeed the only effectual ventilation.”[141]

“The inspector of the road, who accompanied me, thought the opening in the shaft of some use, and said the men wanted it. The superintendent thought it of no use whatever, and that it was something of a nuisance from the water which dripped from it. He was of opinion that after a tunnel was constructed, it would he better to close all shafts, and to trust to quick trains for ventilation. As the tunnel now is, the men continue in it all day, whenever necessary, though they do not like it, but if two freight trains should follow each other without the smoke being cleared away, it would be very difficult for them to work, and if four trains followed each other, it would be impossible.”

In confirmation of the view that tunnels are better for ventilation without shafts, than with them, Mr. Storrow gives the particulars of interesting conversations he had with Mr. Brotherhood and Mr. Brassey upon the subject. Both say that numerous shafts are unnecessary for ventilation. They make eddies and currents, and interfere with each other. Mr. Brassey particularly says, that the passage of a train at quick speed is the best ventilator.

On the whole, although opinions are divided in England, as to the use of shafts for ventilation after a tunnel is completed, it leans rather to the side, that unless in very long ones, shafts are of no use and had better be closed, as they are rather an interference with the natural current which difference of temperature, or prevailing winds, generally occasion; they also interfere with the great ventilating agency of quick trains. A tunnel is compared by many engineers to an inclined chimney; and, as in the upright chimney, the draft would be impaired if there were several openings in its side, interfering with the direct currency of air for ventilation.

The Hauenstein Tunnel (already mentioned in our list of tunnels) is 2,731 yards long; it is straight throughout, and has a uniform gradient of 1 in 139. Three shafts were commenced in the construction of the tunnel—two only were completed, of which one, by a fearful accident through fire, that caused the death of between fifty and sixty persons, became irremediably choked up. The third shaft was used until the completion of the works, but it was closed immediately afterwards, and has not since been opened; the tunnel, therefore, is without ventilating shaft. We have, in the last three years, passed through this tunnel eight or nine times, and, notwithstanding the slowness of the pace, never experienced any inconvenience from want of effective ventilation. Mr. Storrow, who rode on the outside platform of the carriages (they are on the American plan), expresses the same opinion. The conductors of both the trains informed him that there is usually a current of air through the tunnels, and that the smoke disappeared in from fifteen to twenty minutes. Both complained of its being very wet from the dripping of water—a fact that we can fully confirm from personal experience.

Even with goods trains, drawn by two heavy locomotives, which burned coals, although the tunnel was filled with smoke, Mr. Storrow did not find respiration so difficult as what he had often experienced when sitting in a room with a smoky chimney; and he remarked on several subsequent trips the same day, how quickly the tunnel became free of smoke.

The greatest danger to travelling in the Hauenstein, is the falling down, either of portions of the rock, through which the tunnel is pierced, or the giving way of portions of its lining, owing to the water, which is constantly falling, forming into ice. To exclude the cold, as far as possible, a wooden screen, during winter, covers the upper part of the arch at each entrance, descending as far as possible, but allowing sufficient room for the funnel of the locomotive; there are also canvas curtains which may be drawn across the entrance at pleasure, and they are invariably so drawn in winter, except at the very moment of the passage of trains.

The chief engineer of the line is doubtful as to whether there ought not to be a shaft. At times the current of cold air through the tunnel is so strong, that it would be an inconvenience to the trains if not checked by the curtains. They also have the effect of keeping up a temperature in the tunnel sufficient to prevent the water that drips on to the rails becoming frozen in winter. Great trouble and inconvenience were experienced from this cause in the first instance. The freezing of water, lodged on the rails, has scarcely ever happened during the last few years.

The time that a train will take to pass through the tunnel of the Alps must now be considered. If it had been constructed throughout on the level, or with every favourable gradients, and that a train would be permitted to run throughout at express speed, it might be conveyed from entrance to exit in about twelve minutes. This gives a speed of say thirty-eight miles an hour. But with a gradient, the average of which is 1 in 45, anything approaching this rate of speed would be simply impossible.

Length, however, is not the only element that has to be taken into account.

M. Auguste Perdonnet, in his “TraitÉ ElÉmentaire des Chemins de Fer” (Paris 1858-60), says with great truth: “Les fortes pentes sont plus nuisibles dans les souterrains que dans toute autre partie, d’un chemin de fer. L’humiditÉ empechant la boue, qui impregne les rails, de secher, l’ascension de fortes rampes y devient tres penible. Il faut, donc, s’appliquer a les eviter plus encore dans les tunnels qu’a ciel ouvert.” No matter how stoutly the tunnel of the Alps may be lined, and no matter how impenetrably the tunnel may act as a barrier against infiltration of water, it never can be free from moisture; not the moisture of a downfall of rain, which washes the rails and “makes things pleasant,” but it will be one in which will be conbined, unchemically and therefore loosely, the steam of the engines condensed into water, minute particles of grease, and smoke; all three will, inter alios locos, find a resting place upon the rails, and they will thus create on them a thick, clammy, pasty moisture, which will sensibly diminish the engine’s adhesion, and act as a most serious impediment to its progress. It will therefore be impossible with the foregoing elements, and with a gradient of 1 in 45, to calculate on a higher rate of speed from the Modane entrance to the centre than ten miles an hour, or six minutes to the mile—twenty-two minutes; and our belief is that to maintain even this rate of speed it will be necessary to have a fiercely burning fire in the fire-box and tubes, together with a plentiful fall of sand from the sand boxes on to the rails. As soon as the train has arrived at the centre, which is also the summit of the tunnel, the engine will get relieved, and with the gradient almost level the second half of the tunnel can, as a simple question of speed, be run at the highest possible rate. But although it may be safe, it certainly will not be expedient to do so. At twenty-four miles an hour the time required would be nine minutes; total, with twenty-two minutes for the ascent, thirty-one minutes. As regards the journey from Italy to France, Can a higher rate of speed be permitted for the descent of the 429 feet in 3¾ miles than was allowed for the ascent? There appears to us to be but one answer—Certainly not. As regards danger, we believe that with efficient and powerful engines and proper brakes, in the hands of steady and competent men, the transit will not be attended with a particle of danger; but the question arises, Will travellers generally be of this opinion? Many of both sexes will undoubtedly consider that they are as safe in the tunnel as during any other part of their journey; but it is to be feared that the majority of persons who go through it will not only have vividly present in their minds a sense of actual danger from material causes, but also a belief that if they escape any damage from these causes, suffocation must be a natural result of going through seven and a-half miles of foul, fetid, and polluted atmosphere, in a long hole never less than three thousand, and for a tolerable distance five thousand six hundred feet, below the upper and outer surface of the mountain. Death, if it do occur, will be caused, not by actual suffocation, but from some action upon the nervous system, that will produce all the fatal symptoms of suffocation.

We have had no less than three very recent illustrations of death from such a cause, no later in fact than in August 1867; for during that month three inquests were held on three persons who had been taken out in a dying state from the London Metropolitan Railway. In each case the suspension of animation took place between Lisson Grove and King’s Cross Stations, yet the distance (all in tunnel) between them only slightly exceeds two miles, and there are abundant means of ventilation at the three intermediate points, Baker Street, Portland Road, and Gower Street Stations. The verdict in the first case was “accidental death from natural causes, accelerated by the suffocating atmosphere of the Underground Railway.” “Death from effusion of serum on the brain” was the verdict in the second case—in other words, apoplexy; but as the medical gentleman who made the post-mortem examination, could not state at the inquest that the atmosphere of the railway had accelerated death, no reference to it was made in the wording of the verdict.

The third case, happening almost immediately afterwards, excited a good deal of alarm in the public mind; and the alarm was not lessened in consequence of the publication of several sensational articles in two or three London newspapers. Therefore, at the opening of the inquest held upon Elizabeth Stainsley, on the 28th of August, Mr. Myles Fenton, the General Manager of the company, requested an adjournment until time had been afforded to obtain analyses of the atmosphere of the tunnels. Professor Julian Rodgers, of the London Medical School, was engaged by the Coroner; Drs. Bachhoffner, Letheby and Whitmore by the company. At the adjourned inquest, held on the 30th of October, Professor Rodgers submitted his report, in which he stated that he had analysed and tested the air contained in the tunnels of the railway between Bishop’s Road and King’s Cross Stations, and he had made comparative experiments in other tunnels. “The atmosphere in a pure condition,” continued Professor Rodgers, “consisted of a volume of 79·19 measures of nitrogen, and 20·81 of oxygen; and every 10,000 measures of air contained from 3·7 to 6·2 measures of carbonic acid. On the 4th of September he found that, in 17 cubic inches of air taken from each of the tunnels between the hours of 3 and 5 p.m., tested for carbonic acid, with the exception of the air from the Gower Street and King’s Cross tunnel (which contained a more notable quantity), only a slight trace of the acid was indicated. On the 10th of September, between 10 and 11 p.m., he determined the quantity of carbonic and sulphurous acids contained in 17 cubic inches; and during his transit backwards and forwards from King’s Cross to Bishop’s Road he found 13 measures of carbonic acid in 10,000 of air, and one measure of sulphurous acid in 40,789. Carbonic acid was evident in 17 cubic inches of the air taken from the Gower Street and King’s Cross tunnel. On October 2, in the same tunnel, he found 18·7 measures of carbonic in 10,000, and one measure of sulphurous acid in 23,913. On October 28, between 8 and 9 p.m., he found traces of carbonic evident, in 17 cubic inches in all the tunnels. On the 4th of September he found that the following were the per centages of oxygen in the tunnels:—Bishop’s Road, 20·48; Edgware Road, 20·60; Baker Street, 20·30; Portland Road, 20·10; Gower Street, 18·7. In the Blackheath tunnel, on September 28, it was 20·0. The air of Pimlico on September 21 contained 20·9. On October 24 the per centage was as follows:—Box Tunnel, 20·3; Birkenhead Tunnel, 20·1; Wolverhampton Tunnel, 20·5; at Wellington Barracks, 22·42, at 2 feet 6 inches from the floor.”

Replying to the Coroner, Professor Rodgers said he did not think the deficiency of oxygen would act injuriously upon a delicate person passing through the tunnels; and he considered that the amount of carbonic and sulphurous gases in the tunnels could not have been injurious to the woman. There was not a sufficient accumulation of these gases to be of injury to the public health. The woman had eaten heartily, was laced tightly, and had a diseased heart; he, therefore, did not think the deficiency of oxygen could have hastened her death.

The joint report of Drs. Bachhoffner, Letheby, and Whitmore was then read and put in evidence. It stated that the analysers collected samples of the air on three separate occasions:—First, immediately after the trains had ceased running at night; second, just before they commenced running in the morning; and third, in the afternoon, between four and five o’clock, a period of the day when there was generally the largest amount of traffic. The samples, twenty-eight in number, were analysed for sulphurous acid, carbonic acid, carbonic oxide, coal gas, and oxygen. The presence of sulphurous acid having been sought by the most delicate chemical test—namely, its action upon iodic acid and starch, which was capable of showing the presence of one part by volume of sulphurous acid in 100,000 parts of air, but by such test the presence of that acid could not be detected; and from this the analysers concluded that its volume was less than the above in the tunnels. The mean proportion of carbonic acid was about 6 in each volume of 10,000. The amounts of coal-gas and of carbonic oxide were so small as to be barely discoverable. The amount of oxygen in the tunnels and stations was not in any case deficient. These results proved that in no instance was the air found to be vitiated to any material extent, although the air taken in the afternoon was less pure than that taken at night. The presence of sulphurous acid gas in the tunnels and stations, which at times was appreciable to both taste and smell, must not be taken as an indication that this gas existed in dangerous quantities, for as little as one part of this gas in 100,000 parts of atmospheric air was strongly perceptible both to taste and smell. The partial combustion of the wood forming the breaks, when acting upon the tires of the wheels, also produces a pungent smell. The analysers were of opinion that, having regard to the cubical volume of the trains, the short time occupied by them in passing through the tunnels and stations, the large volume of air they displaced, and the increased impetus given to the horizontal movements of the air by the rapidity of their transit, the vitiation of the atmosphere could not be of a serious character, and this accorded with the results of their analysis. The tunnels were dry and free from infiltration of liquid or other matters prejudicial to health. The general health of the employÉs of the company was such as to afford unquestionable proof of the sanitary condition of the air in the tunnels. The report ends thus:—“From the foregoing facts, we are enabled confidently to state that the atmosphere of the Metropolitan Railway is not unwholesome or injurious to health.”

Mr. Fenton, general manager, and Mr. Driscoll, an inspector of the company, having been examined as to the improvements made in the ventilation of the tunnels, and the absence of complaint from employÉs of the company, or from passengers with respect to the atmosphere, the jury, almost without hesitation, returned a verdict of “Death from natural causes.”

The singular fact was elicited at the inquest that the peculiarly “pungent smell” of the tunnel is due rather to the friction of the brakes, than to any other cause. The partial combustion of the wood produces a pyroligneous carbo-hydrogen, as Dr. Letheby styled it, together with a small amount of sulphurous acid gas. These the nose and lungs will detect sooner than the most delicate chemical tests, and they are the real producers of the coughing and unpleasant feeling experienced by some passengers. Such vapours, however, only affect delicate people. This will account for the fact that people, travelling through ordinary tunnels, are free from irritation and coughing. The Metropolitan Railway is the only tunnel in which, owing to stoppages at intermediate stations, it is necessary to put the brakes on.

The efforts made by the company to ensure the best ventilation and purest atmosphere possible, are unremitting. Before the opening of the line an extended series of experiments was made with various specimens of coke supplied by all the leading coke manufacturers in the kingdom. That which best bore the crucial tests, to which the specimens were submitted, is the coke supplied by Messrs. Straker and Lowe from their Brancepeth Collieries near Durham. Coke for locomotives, and other purposes, is usually burned seventy-two hours. When coke of a very superior quality is required (so that all sulphurous and noxious vapours may, as far as possible, be consumed) it is burned ninety-six hours, but all coke used on the Metropolitan Railway is burned twenty-four hours more—that is 120 hours. Special ovens have been built for burning it, and when the process of combustion is completed, the coke is, what is well known in railway locomotive phraseology, “hand picked.” Thus, only the bright coke of each burning is allowed to be sent to London; any outside or dirty coke, however good it may be in reality, being kept back. It is, therefore, impossible to procure, in the whole range of fuel, any more free from ingredients likely to produce unpleasant smell, or to affect respiration.

A few words must be said with respect to the peculiar construction of the engines. In the first place the parts are so arranged that no steam whatever escapes into the tunnel. This is accomplished by having a large tank on each side of the engine. These tanks together contain about 1,000 gallons of water. The exhaust steam is turned into them, instead of through the funnel in the ordinary way. The second peculiarity of the engines is that they are constructed with large heating surface. The steam is raised to a pressure of about 130 lbs. at starting, and by the time the journey through each tunnel, between station and station, is performed, it has been reduced to about 80. The damper is kept on during the entire journey. It will thus be seen that the combustion of fuel in each tunnel must be very small indeed, the fire being simply kept in, without any draft through the fire box.

Recently, the directors of the company, with the view to satisfying public feeling in every possible way, forwarded to the Vestries of St. Marylebone and St. Pancras, applications for permission to effect openings to the external air at several points of the Marylebone and Euston Roads—where important roads cross this thoroughfare—by means of handsome and ornamental hollow columns, which should be connected with the railway, and would support street lamps similar to those now placed at frequented crossings in various parts of the town.

It is a fact beyond all question that, unvaryingly, there are fewer persons belonging to the staff of the Metropolitan Railway, in proportion to their numbers, absent from duty on account of illness, than on other railways. We have seen returns, fully confirming the statement to this effect. We believe they were published by Mr. Myles Fenton, in the newspapers a few months ago.

During the year ending the 30th of June, 1867, the enormous number of 22,458,067 passengers[142] were conveyed by the Metropolitan Railway Company without accident, injury, or (as far as the world knows) ill effects to any one of them.

There is a source of danger in connection with travelling through a long tunnel with a bad gradient, that a recent occurrence in the Dove Hole tunnel of the Midland Railway (a tunnel to which special reference is made at page 372), suggests. The accident is so extraordinary in its character that a brief account of it at present will not he out of place. It appears that on the 9th of September last, a ballast train had gone into the tunnel with the intention of the permanent way men supplying it with ballast. Whilst it was at a stand-still and the men were at work, a cattle train, consisting of twenty-seven trucks, and drawn by two powerful goods’ engines, was permitted to enter the tunnel. This cattle train came into collision with the ballast train, when, among other results, one was that the coupling chain which connected the cattle trucks to the engines broke. The trucks thus freed began to descend the incline, which, as already stated, is 1 in 90; their impetus increased each moment, and by the time they emerged from the tunnel, on the wrong line, they were travelling at express speed. Notwithstanding a slight change in the gradient, they went on at that rate for eight miles, continuing always, of course, on the wrong line. At that point the trucks came in collision with the engine of an express train from Manchester, which had been standing on its own proper line waiting for the signal it should receive before proceeding onwards. The driver of the express train engine perceiving in a moment what was occurring, reversed his engine, put on full steam, and then jumped off, very unfortunately for himself. But the engine had not sufficient speed upon her to prevent a collision with the cattle trucks. The greater part of these latter were literally crushed to atoms; and, perhaps, fortunately, the cylinders of the express train engine were burst by the collision. This allowed a great escape of steam, and it was ultimately, combined with the presence of mind of a pointsman, the means of the engine not doing more mischief than shaking some and frightening all the passengers travelling in the train belonging to it. Not so five drovers who were in the brake-van of the cattle train: they were killed, and, apparently, their deaths were instantaneous. Such an accident as this is not likely to happen in the tunnel of the Alps; but, suppose a coupling iron broke, and with it the coupling chains, on the French or ascending side, would the brake power attached to the carriages be enough to check their downward speed? At all events, it must not be forgotten that the average gradient on the French side of the tunnel is 1 in 45 (117 feet in the mile), or exactly double as steep as that of the Dove Hole Tunnel, and that the Modane entrance of the tunnel of the Alps is 1,216 feet above St. Michel, consequently there is an average fall per mile during the whole twelve miles of 1 in 101, or at the rate of 50 feet in the mile, and as there will be no intermediate station, carriages if they came to be detached, and had not sufficient brake power to arrest their progress, might continue to run the whole of this distance at high speed, and on the wrong line.

[For minute details relating to the construction of the Tunnel of the Alps, up to 1862, and to the means of supplying ventilation during its progress, the reader is referred to the interesting report of Mr. Storrow, embodied in that of the Commissioners of the State of Massachusetts on the Troy and Grenfield Railroad, and of the Hoosac Tunnel, dated the 12th of March, 1863; also, to an article on the Tunnel, in the Edinburgh Review for July 1865, No. 249.]