“Yes,” said Jonas, “I think I can tell you. But do you know what the grain is?”
“No,” said Rollo, “I don’t know any thing about it.”
“You know that boards are made from the stems of tall trees.”
“Yes,” said Rollo.
“Well, now when trees are growing, there are little channels running up and down from the roots to the branches.”
“What are they for?” said Rollo.
“They are for the sap. The sap flows up and down in them. But then there are no channels across from one side of the tree to the other, because there is no sap to go across. The sap all has to go up from the roots to the branches; and so the channels must all be up and down the tree.
“Now,” continued Jonas, “when they cut down the tree, the trunk will split easily, up and down, the way the channels and fibres all go; but it won’t split easily across. And just so, when they saw it up into boards, the boards will all split lengthwise, from end to end, for this is the way the channels and fibres all lie; but it won’t split across, for that would be across all the fibres, and the wood is made very strong in that direction, and it is well it is so.”
“Why?” said Rollo.