But this rate of inclination, of 1 in 45, acquired on some few elevated ridges, as will be seen presently, at an enormous cost, was incapable of general application. Nevertheless, railways had hardly been established on low lands before men’s minds ran upon constructing them over mountains. It is now fully twenty years since the first idea of placing an iron road upon the bed of one or more of the carriage roadway passes of the Alps was promulgated. Of course it found favour, and created interest. Nor can this be matter of wonder when we remember that communication across them has, for centuries, been of world-wide importance. Even if we study the traces that still exist of man’s earliest history in mid and southern Europe, we find that the passage of the great barrier which for more than 500 miles separates north from south, had occupied men’s thoughts and actions from the remotest period. Etruscan tools, coins, and sacred images, have, as we learn from Dr. Ferdinand Keller’s recent work on the _Lake Dwellings of Switzerland_, been found frequently and in abundance, not only on the northern slopes of the actual Alps, but far northward beyond them. We know too, that the ancient Helvites and Gauls were ever seeking the traverse of the snow-capped mountains, that they might exchange their own cold and sterile plains for those on the sunny side, which gave them warmth and luxurious cultivation. By degrees, the early few, savage, daring, and intrepid, increased in numbers; they became masses,—they became colonies. They obtained possession of, and held the districts which in modern times we knew as Venetia, Lombardy, and Savoy; but now they form the northern boundaries of undivided Italy. In the early Roman period, the northern limit of Roman territory extended to the Po, and no farther. Beyond was Cisalpeà, and so it continued until Augustus Cæsar Imperator finally subdued, some thirty years before the birth of Christ, the whole of the warlike tribes, and brought them under Roman subjection. History records but one solitary instance of the vanquished erecting a monument to do honour to their conqueror. This was at Susa, and the inscription on the PORTA CÆSARIS AUGUSTI tells us why it was erected, and what deed it was intended to perpetuate.