FINDING THE HEIGHT OF A TREE

New Zealand Tablet, 25 September 1913, Page 61

FINDING THE HEIGHT OF A TREE

Of all the trees that Billy knew, the very tallest was the great elm in the meadow lot near the river. He heard that the spire of the new church, at the village was more than a hundred feet tall, and he felt sure that his tree was taller than that. One day Billy and his cousin Robert were playing in the meadow. They sat down to rest for awhile in the shade of the great elm. ‘ I wish that I could find out how tall this tree really is,’ said Billy. ‘ Why, that is easy enough,’ said Robert. They ran to the barn, where Robert picked out a small pole from a pile of lumber. With a foot rule, which Billy brought from the house, they found that

the pole measured almost exactly 10 feet in length. Taking both the pole and the foot rule, they hurried back to the meadow. ‘ Now you sit down and watch me,’ said Robert. He stuck the pole into the ground, not far from the elm, but outside the place where its great shadow fell. Then he carefully measured the shadow that was cast by the pole, and with equal care measured the distance from the base of the tree to the end of the shadow cast by its topmost branches. ‘ Your elm is 128 feet tall,’ he said, a moment later, \ < ‘ How did you do it?’ cried Billy. ‘There could be nothing easier,’ said his cousin. * The pole is 10 feet tall, and I found that its shadow is just 5 feet in length. Now that means that it takes 2 feet of the pole, with the sun where it is now, to cast & foot of shadow. Of course it is the same with the tree. I found that the length of the tree’s shadow is 64 feet. This means that the tree itself is twice 64 feet, or 128 feet high. Do you see? That is the way our teacher had us find out the height of our flagpole.’ Billy was quick enough to understand, and before another day had passed he had measured the height of a score of trees in the meadow and near the house.