"True," said Mr. George, "because in America, as that is a new country, there is an abundance of native forests, where the trees grow wild. But you must remember that every foot of land in Europe has been in the possession of man, and occupied by him, for two thousand years. There is not a field or a hill, or even a rocky steep on the mountain side, which has not had sixty or seventy generations of owners, who have all been watching it, and taking care of it, and improving it more or less all that time; each one carefully considering what his land can produce most profitably, and taking care of it and managing it especially with reference to that production. If his land is smooth and level, he ploughs it, and cultivates it for grass, or grain, or other plants requiring special tillage. If it is in steep slopes, with a warm exposure, he terraces it up, and makes vineyards of it. If it is in steep slopes, with a cold exposure, then it will do for timber, provided there are streams near it, so that he can float the timber away. If there are no streams near it, he can use it as pasture ground for sheep or cattle; for the wool, or the butter and cheese, which he obtains from this kind of farming, can be transported without streams; or, at least, such commodities will bear transporting farther before coming to a stream than wood or timber. Thus, you see, whatever the land is fit for, it has been appropriated to for a great many centuries; and it has all been cropped over and over again, even where the crop is a forest of trees. If we allow the trees even a hundred years to grow, before they are large enough to cut, that would give, in two thousand years, time to cut them off and let them grow up again twenty times."
"Here comes a steamer," said Rollo.
Just then the bow of a steamer came shooting into view, down the river. On the forward part of the deck were several soldiers and laborers, with women and children that looked like emigrants, and also a huge pile of trunks and merchandise covered with a tarpauling. Then came the paddle wheels, and then the quarter deck, with a large company of tourists, most of whom were looking about very eagerly at the scenery, with guide books and glasses in their hands. These were tourists that had been travelling in Switzerland, and were coming home by way of the Rhine; and as they were now just entering the part of the river where the grand and imposing scenery was to be seen,—though Mr. George and Rollo were just leaving it,—they were full of wonder and admiration at the various objects which appeared around them on every side. Rollo had but a very brief opportunity to look at these strangers, for the steamer which conveyed them passed by very swiftly, and in a moment they were gone.
"How swift!" said Rollo.
"Yes," said Mr. George, "they go down the stream much faster than they go up; for in going down they have the current to help them, but we have it to hinder us in going up."
"And does it help just as much as it hinders?" asked Rollo.
"Yes," said Mr. George, "for any given time. If the current flows two miles an hour, it will carry forward a boat that is going with it just two miles faster than it would go in still water. And if the boat is going against it, it will go just two miles an hour slower.
"Thus, you see," continued Mr. George, "if a steamer had an engine capable of driving her twelve miles an hour through the water, in navigating a stream that flows two miles an hour, she would go fourteen miles an hour in going down, and ten miles an hour in going up."
"Then," said Rollo, "it seems that the help of a current is just as much as the hinderance of it, and that a river running fast is just as good for navigation as if the water were still. Because, you see," he added, "that though they lose some headway in going up, they gain it just the same in coming down."
"That reasoning seems plausible," replied Mr. George, "but it is not sound."