there now."

Just then Rollo heard a rapping sound upon the stone of the sidewalk
near him. He looked round to see what it was. There was a blind man
coming along. He had a stick in his hand, which seemed to be armed at
the lower end with a little ferule of iron. With this iron the blind man
kept up a continual rapping on the flagstones as he slowly advanced. The
iron produced a sharp and ringing sound, which easily made itself heard
above the thundering din of the carriages and vans that were rolling
incessantly over the bridge, and served as a warning to the foot
passengers on the sidewalk that a blind man was coming. Every one
hearing this rapping looked up to see what it meant; and, perceiving
that it was a blind man, they moved to one side and the other to make
way for him. Thus, though the sidewalk was so crowded that a person with
eyes could scarcely get along, the blind man, though he moved very
slowly, had always vacant space before him, and advanced without any
difficulty or danger.[B]

[B] See frontispiece.

"Think of a blind man in such a crowd as this!" said Rollo.

"Yes," said Mr. George.

"And he gets along better than any of the rest of us," said Rollo.

"Yes," said Mr. George, "so it seems."

"The next time I wish to go through a crowd," said Rollo, "I mean to get
a cane, and then shut my eyes and rap with it, and every body will make
room for me."

"Look round here a minute more," said Mr. George; "there is something
else that I wish to explain to you. You see there are no bridges below
this, though there are a great many above."

"Yes," said Rollo; "and how do they get across the river below here? Are
there ferry boats?"

"I think it likely there are ferry boats down below," said Mr. George.
"At any rate, there are plenty of small boats which any body can hire.
They are rowed by men called watermen.

"'Bound 'prentice to a waterman,
I learned a bit to row.'"

"What poetry is that?" said Rollo.

"It is part of some old song," said Mr. George. "Look down the river and
you can see these boats cruising about among the shipping."

"Is that the way they get across the river below here?" said Rollo.

"Yes," said Mr. George; "and then there is the Tunnel besides. They can
go _under_ the river through the Tunnel if they please, about a mile and
a half below here."

"Is that the reason why they made the Tunnel," said Rollo, "because they
could not have any bridge?"

"Yes," said Mr