Mont Oems, a mountain between the province of Turin in Italy and the department of Savoie in France, at the junction of theGraian with the Cottian Alps. It is an elevated plateau 6,773 ft. above the sea level, with a peak rising to the height of 11,457 ft. On the plateau is Lake La Ramasse, noted for its fine trout. There is little vegetation, on account of the force of the winds which blow constantly. Over this plateau or neck, formed by a gradual sinking northward from the summit of the chain, is what is styled the pass of Mont Cenis, at some distance from the mountain itself. As a practicable pass from Gaul to Italy it was unknown to the ancients. Two centuries before Christ, Hannibal went past it for 40 m., and is supposed to have crossed the Alps at the Little St. Bernard. It first appears in history as an Alpine pass in A. D. 755, when Pepin led his army against Astolphus, king of the Lombards, in aid of Pope Stephen III. Pepin's son Charlemagne led an army over the same route. In 1174 it was crossed by Frederick Barbarossa. In 1557 the duke of Alva passed over with a Spanish army to quell the revolt in the Netherlands. In 1691, in the wars of Louis XIV., Marshal Catinat led the French army across, and made some improvement in the road; but for centuries it was little more than a mere mule path.

In 1803 Chevalier Fabroni, under the orders of Napoleon, began the construction of a carriage road, which was completed in 1810, at a cost of 7,500,000 francs. This highway, 18 ft. wide, extending from Saint-Michel on the western side to Susa on the eastern, would give a distance in a straight line of 30 m., but the windings of the road make it 50 m. An excellent diligence service was established; horses were changed as rapidly as on the best post roads; and at the zigzags, beginning at Lanslebourg on the west side, teams of 16 mules were attached to drag the diligence up the steepest ascents, while many of the passengers dismounted and materially shortened the distance for themselves by walking directly across the long curves. The road was open and safe at all seasons, even in winter, and for many years it was believed to be the only practicable way of crossing the Alps at this important point. Meanwhile railways on either side had reached the foot of the mountains, and about 1861 Mr. Fell, an English engineer, conceived the idea of overcoming by steam transit the gradients of the pass, by applying a principle patented more than 30 years before by Charles Vignolles and John Ericsson, and first tried by them on the Cromford and High Peak railway in England. In 1805 Fell obtained from the French and Italian governments a grant to lay down a railway on Napoleon's Mont Cenis carriage road; it was constructed at a cost of £8,000 per mile, and opened in 1808. The main feature of his plan was the addition of a third central rail, raised a foot above the others, and, by means of brakes and levers, strongly gripped by horizontal driving wheels, thus enabling trains to traverse curves of short radius, and safely to ascend and descend gradients of 1 in 15, and even 1 in 12. From Lanslebourg the track reaches the summit, 4,400 ft. above Saint-Michel, in six zigzags, with a gradient of 1 in 15 to 1 in 12 1/2, in a distance of 6 3/4 m.

At the summit there is a nearly level run of 5 m., and then begins the descent on the Italian side to Susa, over a line extended to a length of 20 m. by a series of zigzags so continuous that the view changes every moment. The train slides down by its own momentum, and all the mechanical power is applied to the centre brake which checks and regulates the speed. But as this road superseded Napoleon's carriage road, on which the greater part of the line was laid, so it in turn has been superseded by the Mont Cenis tunnel railway, completed in 1871. While it was in use travel was occasionally suspended by snow and floods, though wherever there was danger from avalanches the line was thoroughly protected by covered galleries. The idea of a tunnel through the Alps was conceived more than 40 years ago. In 1832 Joseph Medail, a peasant of Bardonecchia, presented to the king of Sardinia a plan for connecting Piedmont and Savoy by a railway tunnel from Bardonecchia to Modane; and in 1843 this plan, accompanied with many particulars, was approved by the chamber of agriculture and commerce at Chambery. In 1845 the Sardinian government invited the engineer Maus and the geologist Sismonda to prepare designs for making a tuntiel through Mont Cenis; and Maus, turning his attention to creating a machine for cutting rock rapidly, was ready in 1849 to present to the-commission at Turin a plan for tunnelling the Alps. The defects of his plan were the cost, want of ventilation, and waste of motive power.

Daniel Colladon of Geneva discovered more perfect means of ventilation, and also of transmission of force; and an English engineer, Thomas Bart-lett, invented an ingenious machine for rapidly perforating rocks. These two inventions, modified by the engineers Sommeiller, Grandis, and Grattoni, with further plans of their own, were presented to the Sardinian parliament in June, 1856, and experiments for perforating the Alps were authorized and begun at Coscia. These were so successful that parliament approved the project of the Alpine tunnel, and the work was inaugurated by the king of Sardinia, who fired the first mine Aug. 31, 1857. In October and November piercing by hand was begun at the two extremities, and a large force was also employed in the construction of roads, water channels, magazines, offices, storehouses, and houses for workmen. The waters of the Arc on the north side, and of the Mele-zet on the south, were utilized for the hydraulic machines which compressed the air supplied to the tunnel.

In January, 1861, the perforating machines, worked by compressed air, were introduced on the south side at Bardonecchia, and in January, 18(53, on the north side near Modane. The work was carried on successfully night and day till Dec. 20, 1870, when the two bodies of workmen met and the tunnel through the mountain was complete. The progress of the perforation, nearly 8 m., was as follows: on the Bardonecchia side, from 1857 to 1861, by hand, 2,379 ft.; from 1801 to 1871, by machines, 20,851; on the Modane side, from 1857 to 18G3, 2,366; from 1863 to 1871, by machines, 13,886; total for the two entrances, 39,482 ft. The mechanical means were water-column compressors, pump compressors, and perforating machines. The number of workmen employed was 1,500 in winter and 2,000 in summer at each entrance. When Savoy in 1860 was annexed to France, an agreement was made between the French and Italian governments by which Italy was to execute the entire work within ten years, receiving from France about 32,000,000 francs for one half of the expense.

The total cost of construction was about 75,000,000 francs, or $15,-000,000. The Mont Cenis tunnel (improperly so called, as it is 16 m. from the mountain) was opened for railway travel Sept. 17, 1871. The elevation of the southern entrance above the sea is 4,237 ft.; of the northern entrance, 3,802; of the culminating point, 4,247. The tunnel is broad enough for two double lines of rails. The railway does not run in a straight line through the tunnel; the entrances are left open only for ventilation, and the tracks are laid in junction tunnels, on the south of the length of 2,484 ft., and on the north of 1,488. (See Tunnel.)

Mont Cenis Railway.

Mont Cenis Railway.