Every now and then we plunged in and had a swim. Every projecting grassy cape had its joyous group of naked children, the boys to themselves and the girls to themselves, the latter usually in care of some motherly dame who sat in the shade of a tree with her knitting. The little boys swam out to us, sometimes, but the little maids stood knee-deep in the water and stopped their splashing and frolicking to inspect the raft with their innocent eyes as it drifted by. Once we turned a corner suddenly and surprised a slender girl of twelve years or upward, just stepping into the water. She had not time to run, but she did what answered just as well; she promptly drew a lithe young willow bough athwart her white body with one hand, and then contemplated us with a simple and untroubled interest. Thus she stood while we glided by. She was a pretty creature, and she and her willow bough made a very pretty picture, and one which could not offend the modesty of the most fastidious spectator. Her white skin had a low bank of fresh green willows for background and effective contrast--for she stood against them--and above and out of them projected the eager faces and white shoulders of two smaller girls. Toward noon we heard the inspiriting cry,-- "Sail ho!" "Where away?" shouted the captain. "Three points off the weather bow!" We ran forward to see the vessel. It proved to be a steamboat--for they had begun to run a steamer up the Neckar, for the first time in May. She was a tug, and one of a very peculiar build and aspect. I had often watched her from the hotel, and wondered how she propelled herself, for apparently she had no propeller or paddles. She came churning along, now, making a deal of noise of one kind or another, and aggravating it every now and then by blowing a hoarse whistle. She had nine keel-boats hitched on behind and following after her in a long, slender rank. We met her in a narrow place, between dikes, and there was hardly room for us both in the cramped passage. As she went grinding and groaning by, we perceived the secret of her moving impulse. She did not drive herself up the river with paddles or propeller, she pulled herself by hauling on a great chain. This chain is laid in the bed of the river and is only fastened at the two ends. It is seventy miles long. It comes in over the boat's bow, passes around a drum, and is payed out astern. She pulls on that chain, and so drags herself up the river or down it. She has neither bow or stern, strictly speaking, for she has a long-bladed rudder on each end and she never turns around. She uses both rudders all the time, and they are powerful enough to enable her to turn to the right or the left and steer around curves, in spite of the strong resistance of the chain. I would not have believed that that impossible thing could be done; but I saw it done, and therefore I know that there is one impossible thing which CAN be done. What miracle will man attempt next?