The "wireways" by which much of this unique transportation was accomplished are of Italian invention, as were other notable and essential engineering devices of this great war of mountain transportation. Such contrivances, known as "teleferrica," were introduced for the first time during the winter of 1916, and by summer there were about 200 along the mountainous front. They not only supplied very advanced positions with armament, ammunition and food, but transported men back and forth between them and lower points. SYSTEM ONE OF TACKLES. The system was one of tackles (where guns and other heavy freight were to be moved) or cars (like cradles, where men were to be moved), operated by motor-pulleys directly connected up with great electric power. One of the most astonishing and picturesque uses to which these aerial wireways were put was the movement downward of men wounded at the advanced posts with which the teleferrica communicate. To see wounded men going down these wireways, mere dots, each representing a suspended stretcher upon which a suffering human being is strapped securely, was described as one of the most amazing spectacles of the whole war. The experience, to some wounded men, swinging sickeningly, dizzyingly alone in midair, was probably more terrifying than actual fighting, although there were few, if any, accidents connected with the wireways. Not infrequently these wireways were within direct range of the enemy fire, and that complicated matters. So far as is known, there has been no instance of a cable cut by gunfire, but in several districts it was necessary that the men, going to their duty and the wounded going backward, having done theirs, must needs be protected in armored baskets, somewhat like those which often are swung beneath observation balloons on the various fronts. PROBLEMS OF TRANSPORTATION. The problems of transportation, great as they are, are by no means the only unique difficulties presented to these brave mountain fighters. In this extraordinary warfare mining by means of high explosives was carried on upon a hitherto unequaled scale. Such work with high explosives was not only continually necessary in the construction of roads and fortifications in a region of solid rock, but sometimes proved the only effective means of attack upon the enemy. The mine was used as an offensive weapon by both sides, and often with very terrible results. Perhaps the most extraordinary of the campaign was the mine laid by the Italians after infinitely difficult and very extensive tunneling in solid rock at the Cima del Col di Lana. This immense effort with explosives blew off the whole top of a mountain--and that mountaintop was thickly occupied by Austrians at the time of the explosion of the mine. None on the Italian side knows exactly what the Austrian casualties were, but it is certain that through this one explosion more than an entire company--that is, more than 400--of the enemy's soldiers were destroyed.