Many rocks, here and further down, have been blasted away to improve the navigation; and this has no doubt made the Strudel less dangerous to appearance as well as in reality. Rocks used to be visible at low water dividing the rapids into three, and these and the submerged rocks were all named by the boatmen. They have, however, been removed by modern engineering so that when the water is even low enough to leave the bed of the Hössgang, or right branch of the river bare, no Strudel rocks are visible. The Hössgang is said to have originated in a farmer’s having cut an irrigating channel into the low-lying land that now forms the island, and to have been enlarged by the force of the impetuous current. A little below the Strudel is the Wirbel, which was at one time more dreaded as a “whirlpool” than the rapids we have just mentioned, but the improvement of the navigation has done away with the second of these twin terrors of the old-time boatmen and now we have to be told when we are passing the one-time place of dread, for the tower-crowned rock that divided the channel and formed the phenomenon was some years ago entirely cleared away. More than sixty years ago Dr. Beattie declared prophetically that “if the rock called Hausstein were blown up it is probable that this whirlpool would entirely disappear.” How effectually this has been the case the present-day visitor acquainted with the old accounts of the terrible Wirbel will soon ascertain. Before dealing with the Wirbel it may be interesting to quote Planché’s account of his passage of this part of the river, describing it as it was before the channel had been cleared: “As soon as a bend of the river has shut out the view of Grein and its château, a mass of rock and castle scarcely distinguishable from each other, appears to rise in the middle of the stream before you. The flood roars and rushes round each side of it; and ere you can perceive which way the boat will take, it dashes down a slight fall to the left, struggles awhile with the waves, and then sweeps round between two crags, on which are the fragments of old square towers, with crucifixes planted before them. It has scarcely righted itself from this first shock, when it is borne rapidly forward towards an immense block of stone, on which stands a third tower, till now hidden by the others, and having at its foot a dangerous eddy. The boat flashes like lightning through the tossing waves, within a few feet of the vortex, and comes immediately into still water, leaving the passenger who beholds this scene for the first time, mute with wonder and admiration. These are the Scylla and Charybdis of the Danube, the celebrated Strudel and Wirbel. The passage is made in little more than the time it takes to read the above brief description, and I could scarcely scratch down the outlines of these curious crags and ruins, before I was whirled to some distance beyond them.”