Ferney, though so near to Geneva, is within the confines of France, and the carriage passed the line between the two countries in going home. There was a little custom house and two or three armed policemen at the frontier; but the party of travellers were not molested, and so in due time they arrived safely home.
Chapter VII.
The Junction of the Arve.
One evening, when Rollo was walking with his father and mother on one of the bridges which led over the river, they stopped at a place where two boys were fishing, and looked down over the railing into the water. The water was quite deep, but they could see the stones on the bottom of it almost as distinctly as if they had been looking only through the air.
"How very clear the water is!" said Mrs. Holiday; "and what a beautiful tinge it has! What is the reason of it?"
"I don't know what the reason is of the blue tinge," said Mr. Holiday; "but the cause of its being so clear is, that it flows out of this great lake, where it has been lying so long that it has had time to settle perfectly.
"There is a great difference in the streams of Switzerland," continued Mr. Holiday. "Some are exceedingly clear, and some are exceedingly turbid. There are two ways by which the turbid waters become purified. One is, by being filtered through the sands under ground; and the other is, by 'settling', as we call it, in the lakes. The water of the fountain that we saw on our way to Ferney was beautifully clear, and it was made so by filtration in the sand, in coming down through the heart of the mountain. This water, on the other hand, is made clear by its impurities subsiding in the lake."