O you remember," asked Uncle Paul, "what happened
last winter to the garden pump—that handsome red
copper pump that shines so in the sun? You have some
idea how a pump is made. Below there is a long lead
pipe that runs down into the well, while above is a
short thick pipe in which the piston goes up and down.
This thick pipe is the body of the pump.
"One very frosty morning the pump was found burst from
top to bottom; there was a crack as wide as your
finger, and out of this crack projected a strip of ice.
It caused such a commotion in the house! It was
wash-day, and the pump would not work. Mother
Ambroisine spent all the morning fetching water from
"I think," said Jules, "they said the cold had burst
the pump; but I racked my brains without being able to
understand how cold could burst a metal pipe. An iron
or copper pipe is so hard!"
"And then, Uncle," put in Emile, "that same night, the
night of the hard frost, I had left my pen-holder, a
small metal tube, on the bench in the garden. I found
it again in the morning not damaged in the least. How
had it stood the cold when the big strong pipe of the
pump had burst?"
 "That will all become clear," his uncle replied, "if
you will listen to me."
"We are listening with both ears, Uncle Paul," Emile
returned, eager for the explanation.
"It is true the cold had burst the pump, but not the
cold alone. There was something in the body of the
pump, there was—"
"There was water," Jules hastened to interpose.
"This water, when the cold came, was turned into ice
which found itself imprisoned between the body of the
pump and the piston, without being able to move either
up or down. Now, I must tell you that ice expands as it
forms. It expands so much that if it happens to be
imprisoned it pushes this way and that, in all
directions, and breaks the obstacle that arrests its
expansion. So the body of the pump burst because ice
"Then the tube of my penholder was not burst by the
cold because there was no water in it?" asked Emile.
"But if there had been water there which could not get
"It would most certainly have burst."
"That will be a fine experiment for next winter."
"Speaking of experiments, I will tell you of one that
will show you the power of ice when it forms and
expands in an enclosed space. What is more solid than a
cannon? It is made of bronze, a metal almost as
unyielding as iron; it weighs several hundred pounds;
and its cylindrical wall is a hand's breadth or more
thick. The cannoneer loads it with
 a small sack of powder and a ball that Emile would find
it hard to lift. The powder takes fire, there is an
explosion like a clap of thunder, and the iron ball is
shot to the distance of a league or ever farther. Judge
then the resistance this terrible engine of war must
"Well, the expansive force of ice has been tried on
cannons. A cannon is filled with water and its mouth
stopped up with a solid iron plug screwed so tight that
it cannot move. Then the whole is exposed to the cold
during a severe winter day. The water freezes and soon
the cannon is split from end to end, the ice crowding
out through the cracks. What wonder that the pipe of a
pump bursts under pressure of ice, when a cannon is
rent like an old rag? I must tell you further that this
rupture under the pressure of freezing water is
accomplished in the quietest way. There is no
explosion, as you might imagine there would be, no
scattering of flying fragments in every direction.
Without any noise the metal is forced apart, and that
is all. Should you be sitting astride the cannon, you
would have nothing to fear when the rupture came."
The children listened very attentively, being much
interested in the bursting of a cannon by something
apparently so harmless as ice. But in one particular
they were left unsatisfied: they had no opportunity to
test for themselves the power of ice. Their uncle read
their thoughts, and added:
"There is not much chance of your ever witnessing the
bursting of a cannon by ice, and your eyes tell me that
you are waiting for me to suggest some
 substitute. Well, then, how will this do? Next winter
take a bottle, fill it full of water, and then cork it
securely with a good stopper tied down with string. Put
your bottle out of doors when there is a sharp frost.
Sooner or later you will find it in pieces, broken by
the pressure of the ice. Here again there is no danger.
The pieces of the bottle are not sent flying all about,
but remain close together, clinging to the ice; or else
they fall harmlessly to the ground. That will be an
experiment more worth while than the one with the
penholder. Try it when winter comes."
"We certainly shall," Jules responded. "It will be a
curious sight. I have an idea, Uncle Paul; let me tell
it to you. In the new pump that was put in to take the
place of the old one when that was burst, there is a
tap at the bottom; and when it seems likely that there
will be a hard frost Mother Ambroisine always goes and
opens the tap to let the water run out. That must be to
keep ice from forming inside the pump?"
"Yes, that is it. Moreover, as one might forget to open
the tap, it is prudent during very cold weather to wrap
the pump with rags or straw to shelter it from the air
and prevent its getting too cold. That is a precaution
to be taken next winter."