Well, of course, the very first thing that Charlie wanted to do was to go and sail his boat—but what do you think? The brook was so shallow and full of stones that there was no place deep enough to sail the boat at all! That was very sad.

Charlie and his Daddy walked a long way beside the brook looking for a pool where the water was deeper, but they could not find one.

Then Charlie’s Daddy said, “Well, unless some rain comes to make the brook get deeper, I guess you’ll have to wait to sail your boat till you come back to town and can sail it in the bath tub. As long as you are in the country you will have to say that the boat is in ‘dry dock.’”

But what do you think? Charlie didn’t even know what a dry dock is. No, his Daddy had to explain to him all about it—how the ship is put into “dry dock” when it has to be mended or painted below the water line. First the ship sails into the dock, and then the dock is closed up behind the ship and all the water is pumped out and the ship is propped up straight with props from each side of the dock.

So Charlie and his Daddy made a dry dock for his ship on the bureau in his room. They made the dock of books, and propped the ship up straight with blocks on each side of the keel. The ship looked very beautiful on the bureau, but Charlie did wish that he could sail it and that he did not have to keep it in “dry dock” all the time.

One day, when his Daddy had gone back to town, Charlie and his Mother and his Auntie went for a walk.

They went for a new walk. Instead of just going along the road, they thought it would be interesting to follow the creek. So they climbed a wall and followed the creek through the fields and into a wood which was “private property”; but there was a sign which said people could walk there if they did not do any damage.

Then they came to a place where there was a stone wall built right across the creek from side to side and above the stone wall was a great e-nor-mous pool! And the water pounded over the stone wall like a waterfall. The pool was very deep and wide, but above the pool the creek was all stony and shallow again.

Charlie was very much interested. He said, “Why is that stone wall built across the creek, and what makes that pool so deep and broad when the rest of the creek is shallow and narrow?”

Then his Mother explained to Charlie all about it. She explained to him that the pool was a swimming pool, and that the stone wall built across the creek from side to side was a dam. The dam keeps the water in like a basin until it gets as deep as the dam is high and then the water flows over the top.