The tremendous task of cutting or blowing away masses of rock from the river channel took about eight years, and during the winter the workmen occupied Worth Island. The Horse-Shoe water-course, built of freestone, skirting the north side of the island, was planned by the engineer Liske, and the great undertaking was completed by blowing off tons of the Kellerrock, a length measuring over 160 feet. The second terror, the Wirbel, has now altogether disappeared. It was a whirlpool occasioned by the meeting of the two streams which flowed fast around a long tongue of rock 18 feet or so above water normally and 150 yards long by a third as broad. This was less than three-quarters of a mile below the Strudel, and boats and rafts just recovered from the one had to plunge into the eddies and whirlpools of the other at very great risk of being swamped altogether. The cause was in reality simple enough and easily to be understood, being that one stream came up against the impetuous force of the other almost at right angles, but the peasant mind, revelling in the supernatural, invested it with all the mystery of the unknown, and strange tales of weird wraiths rising from unfathomable depths added to the terrors of the passage, and the great circles of the eddying water, reaching sometimes to 50 feet in circumference, were looked upon as a kind of trap peopled by sirens. This was hardly wonderful, as at times the inside vortex was 5 feet deep like a funnel or cup. [Illustration: RUMANIAN CHILDREN BRINGING WATER TO BE BLESSED IN THE GREEK CHURCH, DESZE] The railway which we met at Linz took a curve to the south, and it is not until after the junction with the river Ybbs we meet it again. The white castle of Persenbeug stands up conspicuously near, with the town of the same name close at hand. The castle of Weiteneck, the monastery of Mölk, are both wonderful, but the latter compels the greatest attention. It is huge and completely eclipses the little town attached to it. The grandeur of its lines, the splendour of its interior finish, mark it out as a palace among monasteries. Its cupolas and long ranges of windows give it an individual note. Inside, the library is a truly princely room, no less in its adornment than the valuable books and manuscripts it contains. Enough has been said to show that the stretch of the Danube between Passau and Vienna fairly bristles with scenic and historic interest, but two more castles at least must be mentioned, that of Aggstein, standing aloof and remote on its towering pinnacle of rock, and that of Dürrenstein, where Richard Cœur de Lion was imprisoned. In the good old days, when might was right and opportunity justification, these robber barons, perched on their mountain tops, commanded the reaches of the river and levied toll to their liking on the luckless men whose business compelled them to pass by water.