The wonderful effects of water in breaking up the hardest rock have already been described. We will now proceed to another branch of the same subject.
Perhaps some of my readers may have wandered along our rocky coasts, and have seen how large masses of rock are continually detaching themselves, though they are so hard that a cold chisel is needed to make any impression upon them.
Then they fall into the sea, and are rolled backwards and forwards until they become smoothed and rounded, and are called pebbles, while the portion that is rubbed off them is called sand. The phenomenon is well shown in the wonderful Pebble Ridge of North Devon.
The real agent is ice.
We all know that, when water freezes, it expands considerably. This accounts for two phenomena.
First, as it expands, it becomes lighter than water, and consequently floats on the surface.
Next, there are few of us who have not seen water-bottles cracked by the freezing of the water. The most common, and perhaps the most unpleasant, example of this propensity is the bursting of water-pipes in the winter, followed by a flooding of the house when the thaw comes.
This is caused by the expansion of the frozen water, which will burst not only a thin leaden tube, but a stout iron vessel. Care should therefore be taken, at the beginning of winter, to cover up all exposed portions of leaden pipes, and there will then be no danger. There was one pipe in my house that was always bursting, but after I covered it with two or three layers of carpet placed loosely over each other, so as to entangle the air and form a non-conductor, the pipe has never frozen, and the water supply has been uninterrupted by the severest frosts.
I am told that a still better plan exists, especially in places where the pipes cannot be thoroughly protected by external wrappings. Let six inches or so of the leaden pipe be removed, and its place supplied by a vulcanised india-rubber tube.