"Why, father," exclaimed Susie, "how could you tell?"
"Do you know how the end of a log looks when it is sawed off straight?"
"I do," said Frank. "There are light and dark rings in it."
"Well," was the reply, "one of these rings grows every year."
"So if you count the rings you can tell how old the tree is," said
Donald. "Isn't that great!"
[Illustration: End of a log.]
"What time of the year do the trees grow the most?" asked Uncle Robert.
"In the spring I should think," said Frank. "That's when the sap begins to run."
"What is sap?"
"It must be the water that the trees take up from the ground," said
Frank.