“Oh, the life guard at the station on the beach would have seen them in time,” returned Mr. Burnett.  “But I’m just as glad we got them when we did.”

“What made you go off in the boat?” asked Daddy Bunker of Margy.

“We didn’t mean to,” answered Mun Bun.  “We got in to play sail, and the boat went off by itself.”

And this was about all the two children could say as to what had happened.  They had got into the boat, which was tied to the pier, and had been playing in it for some time.  Then, before they knew it, the boat became loose, and drifted off.  Russ, who had been playing on the beach not far away, had seen them, but not in time to help them.

He had, indeed, called to them to “come out of the boat,” but then it was too late for Margy and Mun Bun to do this.  There was already some water between their boat and the pier.  Then Russ did the next best thing; he called his mother.

It did not take long for the lobster motor-boat to make the run back to Cousin Tom’s pier, pulling the empty rowboat behind.  Mrs. Bunker rushed down and hugged Margy and Mun Bun in her arms.

“Oh, I thought I should never see you again!” she cried, and there were tears in her eyes.

“We didn’t mean to go away in the boat,” said Margy.

“We didn’t mean to,” repeated Mun Bun.

And of course the children did not.  They had been playing in the boat as it was tied to the wharf, and they never thought it would get loose.  Just how this happened was never found out.  Perhaps Mun Bun or Margy might have pulled at the knot in the rope until they loosened it, and the tug of the tide did the rest.

But the children were soon safe on the beach again, playing in the sand, and the alarm was over.

“What makes the water in the inlet run up sometimes and down other times?” asked Violet.

“It’s the tide,” said Russ, who had heard some fishermen talking about high and low water.

“What’s the tide?” went on the little girl.

“The moon,” added Russ.  “I heard Mother read a story, and it said the moon makes the tides.”

“Does it, Daddy?” persisted Violet.  She certainly had her questioning cap on that evening.

“Yes, the moon causes the tides,” said Daddy Bunker.  “But just how, it is a bit hard to tell to such little children.  The moon pulls on the water in the oceans, just as a magnet pulls on a piece of iron or steel.  When the moon is on one side of the earth it pulls the water into a sort of bunch, or hill, there, and that makes it lower in the opposite part of the earth.  That is low tide.  Then, as the moon changes, it pulls the water up in the place where it was low before, and that makes high tide.  And when the tide is high in our ocean here it pushes a lot of water up Clam River.  And when the water is low in our ocean here the water runs out of Clam River.  That is what makes high tide and low tide here.”