Ice

"D 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 the spring."

"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 formed inside."

"Then the tube of my penholder was not burst by the cold because there was no water in it?" asked Emile.

"Exactly."

"But if there had been water there which could not get out?"

"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 offer.

"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."