ing ice is just as strong as gunpowder, only it works more
slowly," said Daddy Blake with a smile. "Powder goes off with a puff,
a flash and a roar, but ice freezes slowly."

"Oh, but when are we going skating?" asked Mab, as she and her brother
started for school, a little later that morning.

"As soon as I can find a frozen pond," said Daddy Blake with a smile.

Well wrapped up, and wearing warm gloves, Hal and Mab went to their
lessons. It was so cold that wintry day, though there was no snow,
that they ran instead of walking. Running made them warm.

"Is my nose red?" asked Mab, when they were near the school.

"Oh, it's awful red!" cried Hal. "Is mine?"

"As red as a boiled lobster!" laughed Mab. "Let's run faster!"

So they ran, and soon they were in a glow of warmth.

"Oh!" cried Mab, as she and her brother entered the school-yard, "we
forgot to ask Daddy why we get warm when we run."

When the two children reached their house, after lessons were over for
the day, they found their father waiting for them. He had his skates
over his shoulder, dangling from a strap, and he had Hal's and Mab's
in his hand.

"Come, we are going to look for the frozen pond!" he said.

Then Hal and Mab forgot all about asking why they became warm when
they ran. They cried out joyfully:

"Oh, Daddy is going to take us skating! Daddy is going to take us
skating!"

Across the fields they went, and in a little while they came to a
place where was a pond, in which they used to fish during the summer.
But now as they looked down on the water, from the top of a small
hill, they saw that the pond was all frozen over. A sheet of ice
covered it from edge to edge.

"Oh, now we can skate!" cried Hal in delight, "Now we can try our new
skates."

CHAPTER V

POOR ROLY-POLY

"Come on!" cried Mab, as she started to run down the slope of the hill
toward the frozen pond. "Come on, Hal!"

"Hold on!" called Daddy Blake. "Wait a minute, Mab! Don't go on the
ice yet!"

Mab stopped at once. So did Hal, who had just begun to run. You see
the children had gotten into the habit of stopping when their uncle
called: "Wait a minute and I'll give you a penny," so it was not hard
for them to do so when their father called.

"Why can't I go on the ice?" asked Mab,

"I must first see how thick it is," answered Daddy Blake.

"What difference does that make?" Hal wanted to know.

"Oh, a whole lot," said Mr. Blake. "If the ice is too