38 THE STORY-BOOK OF SCIENCE 



"I see them too by looking closely, " chimed in 

 Emile. 



"I must tell you," continued Uncle Paul, "that 

 those circles are called annual layers. Why annual, 

 if you please? Because one is formed every year; 

 one only, understand, neither more nor less. The 

 learned who spend their lives studying plants, and 

 who are called botanists, tell us that no doubt is pos- 

 sible on that point. From the moment the little tree 

 springs from the seed to the time when the old tree 

 dies, every year there is formed a ring, a layer of 

 wood. This understood, let us count the layers of 

 our pear-tree." 



Uncle Paul took a pin to guide his counting ; Emile, 

 Jules, and Claire looked on attentively. One, two, 

 three, four, five They counted thus up to forty- 

 five, from the marrow to the bark. 



"The trunk has forty-five layers of wood," an- 

 nounced Uncle Paul. "Who can tell me what that 

 signifies? How old is the pear-tree?" 



"That is not very hard," answered Jules, "after 

 what you have just told us. As it makes one ring 

 every year, and we have counted forty-five, the pear- 

 tree must be forty-five years old." 



"Eh! Eh! what did I tell you?" cried Uncle 

 Paul, in triumph. "Has not the pear-tree talked? 

 It has begun its history by telling us its age. Truly, 

 the tree is forty-five years old." 



' ' What a singular thing ! ' ' Jules exclaimed. * ' You 

 can know the age of a tree as if you saw its birth. 

 You count the layers of wood; so many layers, so 

 many years. One must be with you, Uncle, to learn 



