you the great mystery, as you
call it, let me tell you how the book you are reading comes out. You
have got acquainted with Little Dorrit, the Father of the Marshalsea,
and----"

"Now, stop! I don't want you to tell me how it comes out!" protested
the fair maiden, vehemently. "I wouldn't have you do it for the world.
It would utterly spoil all the pleasure I might have in reading the
book."

"Is that so? Why shouldn't I explain this great mystery, as well as the
other? I am sure I should deprive you of half the excitement of the
trip if I should tell you beforehand all about it."

"Then you needn't tell me a word!" And I did not.

At lunch-time we were in the midst of another great inland sea, at the
mouth of the Missouri. Some of us wished we were going up that great
river, to explore it where there were no towns, or other evidences of
civilization. As that was not our present purpose, we forgot all about
it as soon as we were out of sight of its mouth. Twenty miles more
brought the fleet to another broad expanse of water, in which were
several islands.

"Adieu to the Mississippi!" I shouted, walking from one end to the
other of the steamer. But I made no further explanation.

There was a call for maps and guide-books then, succeeded by an anxious
study for a few moments.

"This is the mouth of the Illinois River!" exclaimed Miss Margie,
rushing up to me.

"I don't deny it," I replied. To avoid more questions, I went to the
pilot-house.

"We are making about twelve miles an hour," said the pilot of the
Sylvania.

"How can that be? The most we could make in the Mississippi was seven
miles against the strong current."

"The current is the other way here," added the pilot.

"Do you mean that the stream runs up?"

"Precisely that," answered the man, laughing at my perplexity. "When
the Mississippi is very high, it flows the water back in the Illinois
for seventy miles. We get a little current here to help us. After a
while, it will really be still water."

In this part of the river, the stream was full to the top of its banks,
and in some places it overflowed them. The river had furrowed out a
deep channel in the alluvial soil, and at low water, it had tolerably
high bluffs on each side of it. It was almost as wide as the Father of
Waters, where we had left it, at its lower part; but in a few hours the
width began to diminish a little.

Before night, I had called all hands, and, after unbending the
sq