CHAPTER XVII. NARROW-GAUGE RAILWAYS. The art of mining may be said to have given birth to the railway system. Not only was the steam engine primarily employed in mining, and developed in obedience to the necessities of that industry, but long before the use of steam as a motor the idea of traction upon tramways was originated, so far as we can now discover, in mines. It dates back, according to some authorities, to the Egyptians, who made use of this auxiliary in their quarries. But mining has scarcely reaped the full benefit of the combination of steam-power and rails, which has been utilized to so astonishing an extent in commerce and travel. Mines are generally located in more or less mountainous districts, presenting to the railway engineer unusual difficulties of grade and curve, and thus enhancing the cost of construction, while they offer in return a comparatively small amount of remunerative traffic. Railways, on the other hand, have continually tended toward forms of construction involving greater cost and requiring greater income for their profitable maintenance, and have thus been almost excluded from the immediate neighborhood of many mining districts. The coal and iron mines, the products of which are bulky and give rise directly and indirectly to a vast transportation business, form exceptions to this rule. Recently, however, the attention of engineers has been called to two systems of railway construction, which put a new face upon the problems involved. The first of these is the center-rail system, illustrated in the Mont Cenis Railway, which was opened in June, 1868. This method is applicable to mountain passes which have hitherto been considered inaccessible to the locomotive; and the road just mentioned has proved that trains of passengers and goods may thus be safely carried upon gradients and curves which would have previously been considered perilous or impracticable. Up to September, 1870, its trains had run more than two hundred thousand miles, and transported between France and Italy more than one hundred thousand passengers, without injury to a single person. It cannot be claimed for this plan that the direct cost of traction is very small. On the Mont Cenis road, it is reported to have been about 97 cents per train-mile; but there were mechanical defects in the construction of the engines, which will hereafter be avoided on similar lines, and it is believed that the cost of traction can be reduced to half the above sum. Probably the best that can be expected is, that a center-rail line over a difficult country may be maintained and operated at a cost not exceeding that of the maintenance and operation of a line for ordinary engines over the same region; the latter being of course much longer. The principal saving, therefore, is in the original cost of construction; and this might be vast in amount. In fact, we may reasonably presume that ordinary road-beds would never be commercially or financially practicable in most places where the center-rail system will be used. Mr. J. B. Fell, civil engineer, read before the Liverpool meeting of the British Association a paper on the application of this system to a railway in Brazil now under construction. It commences at the terminus of the Canta Gallo Railway, crosses the Serra at an elevation of 3,000 feet above the Canta Gallo line, and terminates at the town of Novo Friburgo, a distance of twenty miles. In some of its principal features this railway resembles the summit line of the Mont Cenis, the gradients for the passage of the Serra over a distance of ten miles being principally from one in twenty to one in twelve, and the curves by which the line winds round the spurs or counter forts of the mountain being, for a considerable portion of it, from 40 to 100 meters radius. The narrow gauge of 1.1 meters has also been adopted. In other features, however, there is an important difference between these two center-rail lines. The concession for the Mont Cenis was but temporary, terminating on the completion of the great tunnel, and the railway is laid on the existing public road, whereas the Canta Gallo line will be permanent, and the works will be so constructed as to be specially adapted to its requirements. It will not have to contend with the difficulties of an Alpine climate; and, profiting by the experience of two years' working on the Mont Cenis, it will have the advantage of important improvements which have been made in the engines, carriages, and permanent way during that period. Consequently, the Canta Gallo, and other similar lines now being or about to be commenced, have the interest of marking an important development of the capabilities and advantages of the center-rail system as applied to the construction and working of mountain railways. In the new engines for the Canta Gallo line, it is proposed to dispense with the toothed wheels, and substitute for them a system of direct driving by connecting rods. The power of adhesion will also be considerably increased. These new engines will have the advantage of being able to run at a speed of from twenty to thirty miles an hour upon the ordinary gradients of the line, and of taking their loads up the mountain section at a diminished speed of from eight to ten miles an hour. In an economic point of view, the result of the application of the center-rail system to the Canta Gallo Railway will be as follows: The cost of construction, assuming it to be as estimated, about £300,000, would be at least doubled if made on gradients upon which ordinary engines could work. In this case the cost of traction and maintenance for a center-rail line will not be greater than for a line with ordinary gradients passing over the same country. The clear saving, therefore, effected by employing the center-rail system is at least £300,000, and the construction of a valuable line of railway has been rendered possible, which would otherwise have been commercially and financially impracticable. Mr. Fell mentioned a somewhat similar line of railway under consideration by the Indian government, from the port of Karwar to Hoobie, in the southern Mahratta country, both by way of the Arbyle and the Kyga Ghats. The distance is seventy miles, and it is proposed to employ the center rail for a length of about ten miles upon gradients of one in twenty for the passage of the Ghat, by which a saving would be effected of about £500,000. The cost at the present time of the transport of cotton and other produce over the ninety miles is stated to be £235,000 per annum, and there is in addition the disadvantage of not being able to convey the whole crop to the port of shipment before the rainy season sets in; a large portion of it has consequently to be housed and kept until that is over. Negotiations are going on with the government local authorities and people interested for the construction of center-rail lines in Italy from the Adriatic to Macerata, and crossing the Apennines to Foligno from Florence to Faenza, and for three branch railways in the Neapolitan States; in France, from Chambery to St. Andre du Gaz |