water on the iron tube. The tube is to be fitted with a tramway of 2 feet 6 inches gauge, on which is to run a light iron omnibus of 10 feet long, 5 feet 3 inches wide, and 5 feet 11 inches high. This will accommodate 14 people with ease. Ordinary lifts will take them down and up the shafts at either end, and at the end of the shaft the omnibus will be waiting. For the first hundred feet or so the omnibus will be pulled by a rope fixed to a stationary engine; after that it will descend by its own velocity down the incline and up the incline on the other side to the foot of the shaft. The whole transit, including time for descent and ascent, is calculated not to exceed 3 minutes. The Artisan.

THE MONT CENIS TUNNEL.

During the past year an advancement of 1,320.15 metres has been made at the Mont Cenis Tunnel, of which 638.60 was driven on the Italian side, at Bardonnêche, and 681.55 metres on the French at Modane. This gives an average advancement of 110 metres per month, or 53.20 on the Italian side, and 56.80 on the French; and at this rate of progress the time necessary for the completion of the tunnel would be 28 months, or about April, 1871, and for opening the railway about 6 months more, or in less than 3 years from the present time.

THE SUTRO TUNNEL.

There is a mountain in Nevada which miners and some geologists believe to contain more than 500,000,000 dollars' worth of silver. Unluckily the veins run through the centre rather than along the slopes of the mountain; and the mines which have been sunk on the great Comstock lode, as it is called, have already reached such a depth that to pump them out and ventilate them is too costly, while no means exist to drain them.

Mr. Adolph Sutro has proposed that a tunnel shall be run into the mountain, which would cut the veins of ore, and serve to drain the mines and open the whole deposit. Here is his present scheme:

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Let 3,000 laboring men pay in an average of 10 dollars per month, which gives you 30,000 dollars per month, or 360,000 per annum, and insures the construction of the tunnel, carrying with it the ownership of the mines. That amounts to 33 cents per day! Who is there among you so poor as to miss it? How many of you expend that much every day in stimulants, cigars, and other luxuries? Put that money into the tunnel; it is laying up something for a rainy day. The money will be expended directly again in labor among yourselves, under your own direction, and from dependents you will become masters."

It is reported that the miners are responding to this appeal, and that Mr. Sutro is not unlikely to get the money. This would be a gigantic co-operative enterprise; one worthy of the age, and of the energetic and determined men who have developed the mining

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regions of the far West. An act of Congress has given to the Sutro Tunnel Company the ownership of all freshly discovered and unworked deposits of ores which may be cut by the tunnel. If Mr. Sutro's theory is correct, of which he at least entertains no doubt, the tunnel would open a mass of silver sufficient to make independent the whole 3,000 miners, from whom he asks 30 cents a day. Evening Post, Oct. 29.

THE PROPOSED TUNNEL UNDER THE BRITISH CHANNEL.

The conditions on which the success of this enterprise depend are comparatively few and simple. The first condition relates to the geological formation in which the work would have to be done.

It has frequently been pointed out, and there appears to be no difference of opinion on the subject, that there are to be found, on opposite sides of the Channel, tracts of coast presenting geological features almost identical. The English coast between Deal and Folkestone, for instance, corresponds in every particular with 3 miles of the French coast, a little to the westward of Calais. That the same formations continue under the bed of the sea is a probability that has been noticed in a report to the Geological Society on "The Chalk Ridges which extend parallel to the Cliffs on each side of the Channel tending towards the North Sea," by Captain J. B. Martin, in 1839. Careful geological investigation has been made with a view to discovery whether the chalk formations obtaining on each coast continue unbroken for the whole distance dividing them; and there appears no reasonable cause of doubt that this is the case.

Impressed by these facts, Mr. William Low, an engineer who for many years had been confident of the feasibility of connecting the English and French railway systems by means of a subchannel tunnel, set himself earnestly to examine for himself the geological formations of the two shores. After most careful examination, Mr. Low became satisfied that the deductions of the geologists were correct. His examination of the borings for several artesian wells on both sides of the Channel strengthened his opinion as to the regularity of the strata. It became his firm conviction that along a certain line, about half a mile west of the South Foreland, and 4 miles west of Calais, the tunnel could be made entirely through the lower, or gray, chalk, which, owing to its comparative freedom from water, and other qualities, would be a most desirable stratum in which to work. With the result of these investigations, and with plans of the tunnels he projected, Mr. Low, in 1867, betook himself to the Emperor of the French, who, giving the English projector a cordial reception, desired him further to organize his plans, and to come again when he might be prepared to submit definite proposals.

In 1856, M. Thomé de Gamond, a French engineer of repute, who had for many years been advocating the construction of a tunnel between England and France, obtained, by order of the emperor, an investigation of his plans at the hands of a scientific commission. This body, satisfied with the substantial accuracy

of M. de Gamond's geological conclusions, recommended that his investigations should be practically tested by sinking pits on the two coasts, and driving a few short headings under the sea at the expense of the two governments. Owing possibly to the backwardness of the Great British Circumlocution Office, this recommendation does not appear to have had any practical result. In 1857, M. de Gamond published the upshot of his researches, and the report of the commission; and at the Paris Exposition of 1867, he publicly exhibited his plans. It was very natural that Mr. Low, after his interview with the emperor, should put himself in communication with M. Thomé de Gamond. This gentleman unreservedly placed his experience at Mr. Low's disposal, and, after a time, the results of their joint labors were laid before Mr. James Brunlees. He, after careful examination, consented to co-operate with the two engineers in the prosecution of the work. A committee of French and English gentlemen of influence and position was, by desire of the emperor, formed to further the project; and it is by the executive committee of this body, under the chairmanship of Lord Richard Grosvenor, that the matter is now practically brought before the public.

But the opinions of Messrs. Low and Brunlees, and of M. Thomé de Gamond, received further confirmation.

Mr. John Hawkshaw, whose name is well known to the public at large and to the engineering world, was induced to test the question, and to ascertain, by elaborate independent investigation, the possibility of a sub-channel tunnel. With characteristic care and caution he took nothing for granted, but went himself over the whole ground already traversed by Mr. Low and by M. de Gamond. His geological researches led him to the same conclusions, and his expression of opinion in favor of the gray chalk was very decided. Not even satisfied with the theoretical results of these investigations, carefully though they were made, Mr. Hawkshaw held it necessary to make borings on each coast, at the precise points at which the ends of the tunnel would be situated. Thus Mr. Hawkshaw and the French commission came to the same decision. Now, the well at Calais, from which a considerable part of the geological inferences had been drawn, was at some distance from the spot where it was proposed to begin the tunnel on the French side, and possibly the strata might, in the precise place indicated, not run as anticipated.

This did not, however, turn out to be the case. The actual borings conclusively proved the correctness of the views entertained.

The boring on the English coast was commenced at St. Margaret's Bay, near the South Foreland, in the beginning of 1866, and was satisfactorily completed in 1867. It was carried completely through the chalk and into the green sand, which was reached at a depth of 540 feet below high water. The boring on the French coast, 3 miles westward of Calais, was carried to a depth of 520 feet below high water. It was intended to pass through the chalk as on the English side, but accident frustrated this design.

Simultaneously with these borings the bottom of the Channel was carefully examined, by means of a steamer provided with all suitable apparatus. The main useful results established by these experiments appear to be, that on the English coast the depth of chalk is 470 feet below high water, of which 295 feet are of the gray formation, in which it is proposed to work; that on the French coast, the depth of chalk is 750 feet, 480 being gray; and that there appears to be no room to doubt the regularity of the strata between the two shores along the line proposed.

So, it would seem, first, that the chief condition is satisfactorily insured, and the geological formation of the sea's bed is such as to admit of the excavation of a tunnel through the lower gray chalk; and, secondly, that it is not necessary to go to a depth unsuitable for railway traffic. It is calculated that the approaches to the tunnel can be constructed at gradients not exceeding one foot in 80.

The next point of paramount importance to the travelling public is the question of the safety of the tunnel when made. The dangers most carefully to be guarded against are two: any possible irruption of water from the sea, or from unexpected landsprings; and any deficiency in ventilation.

Engineers are of the opinion that these dangers can all be provided against. Recent borings on either side of the Channel have proved that there need be no fear of land water, and the impermeability of chalk, and the depth below the bottom of the sea, at which the tunnel will be placed, being in no case less than 100 feet, it is maintained that there would be no danger from incursions of the sea-water. The submarine excavations in the Cornish mines are an existing demonstration of the safety of the proposed tunnel.

Ventilation will be secured by means of powerful steam engines, and attempts to raise the necessary funds are wisely to bo postponed until two small headings, or galleries, are driven from each country, connected by transverse driftways. Ventilation would thus be secured in the manner customary in coal mines and works of a similar nature, and the feasibility or otherwise of connecting England and France by a tunnel can be demonstrated.

CANALS.

The great ship canal which is to connect Amsterdam with the North Sea is now once more in progress, the government of the Netherlands having relieved the contractors of certain difficulties which for a time hindered the work. The canal will be about 15 miles in length. The Zuyder Zee is to be shut out from Amsterdam, and the Pampus dam, by which this is to be effected, is already half finished, and the locks and sluices connected with it are in progress.

A ship canal is to be constructed through Schleswig-Holstein to connect the Baltic and the North Seas. The preliminary surveys have been completed. It is thought the Prussian Government will undertake the work of building.

M. de Lesseps, the Suez Canal engineer, having sent some surveyors to examine the desert of Sahara, has, it is said, become convinced that the desert is at its nearest limit 27 metres below the level of the Red Sea, and that the depression continues increasing toward the interior. He therefore thinks that he can make the desert the bed of a large inland sea, by a canal of 75 miles in length, bringing the water from the Red Sea. Besides climatic changes, an easy method of intercourse with Central Africa would be effected if this project could be accomplished.

Mr. Lange, the London representative of the Suez Canal Company, has made some experiments on the canal with a corvette carrying ten Armstrong guns, and driven by engines of 300 horsepower. He has ascertained the following important points: First, the speed necessary to be maintained on a vessel of the dimensions of the ship experimented with, in order to enable a straight course to be steered, is from 3.2 to 3.7 knots an hour. Second, the embankments suffered no injury while the vessel was going at a rate of 5.4 or 6.4 knots an hour. Third, it was found that the loss of speed incurred by the vessel navigating the canal when compared with the rate on the open sea in smooth water, amounted to one-fourth, the same power being employed in both

cases.

STEAM POWER ON CANALS.

A successful application of the principle of low speeds seems to have been made by Mr. Edward Backus, of Rochester. If the result of the several trials made are correctly stated by the inventor of this novel mode of steam propulsion, then the cost of transportation may be reduced about 32 per cent.

The following extract from a letter written by Gen. Quimby, U.S.A., who witnessed two trials of this boat, will convey an idea of the character of this new mode of propulsion:

"In this boat the motive power, steam, causes a wheel located near the centre of the boat to roll on the bottom of the canal, and thus drive the boat in the same manner that the locomotive is propelled by its driving-wheels. The wheel, placed at one end of a lever frame, readily adjusts itself to the varying depths of the water, and its weight, together with the cog-like projections distributed over its circumference, prevents slipping and consequent loss of traction. It has been found that in the whole extent of the Erie Canal there are not to exceed 20 miles in which the depth of the water is too great for the wheel to work well. For very deep water, a screw-propeller wheel is used, and the motive power is changed from the ground wheel to it with the utmost ease and expedition."

PASSAGE THROUGH THE SUEZ CANAL.

The Rob Roy and English merchant-vessel recently passed through the Suez Canal, and the captain writes to the "London Times" the following account of the present condition of this great undertaking, after 13 years have been spent in its construction: