ely 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."

"And it comes in muddy at the other end," said Rollo.

"Not muddy, exactly," rejoined Mr. Holiday, "but very turbid. The
turbidness of it is not mud precisely. It comes from the grinding up of
rocks by the slow march of the glaciers over and among them. Thus all
the streams that come from glaciers are very turbid; and so long as the
waters flow on in an uninterrupted stream they continue turbid; but when
they form a lake, the particles of stone subside, and the water comes
out at the lower end of the lake perfectly clear."

"And then continues clear till it gets to the ocean, I suppose," said
Mrs. Holiday.

"Yes," replied Mr. Holiday, "unless some other turbid stream, which has
no lake to settle itself in, falls into it and pollutes it again.

"That is the case with this river. It is very clear and beautiful here,
where it comes out of the lake, but the Arve comes in a mile or two
below Geneva, and brings an immense volume of turbid water. This makes
the whole river turbid again after the waters of the two rivers have
flowed long enough together to get well mixed, and then it