Have you ever wondered how tall the biggest tree in your yard is? There are several methods you can use to measure it, such as cut it down and measure one end to the other. Another would be to send one of the kids shinnying up the tree with one end of a rope and when he falls out of the top measure the length of rope he went up with. Or, if you would rather, you can use your brain and some mathematics.
Here’s an easy way to get the height. Get a partner to stand beside the tree. Stand back from the tree and hold up a 12-inch ruler out at arm’s length (0 at the bottom, 12 at the top). Move back or forth until to your mind’s eye the tree and ruler are the same length. Hold the ruler steady and see where the top of your partner’s head appears on the ruler. Let’s say it’s at the 3-inch mark. Dividing three into 12 tells you the tree is four times taller than your friend. So if your friend is 5 feet tall, then the height of the tree is 20 feet.
Another quick method involves pretending to lay the tree down. Stand back from the tree and hold up a pencil at arm’s length. Move back and forth until to your mind’s eye the tree and the pencil are the same length. Carefully keeping the bottom of the pencil lined up with the bottom of the tree, rotate the pencil 90 degrees until it appears parallel to the ground. Direct a friend to stand at where the top of the pencil appears to touch the ground. The distance from the partner to the tree is its height.
One more method: Hold your arm out full length in front of you so that your fist is at eye level. Measure the distance from your fist to your eye with a yardstick. Hold the yardstick at that measurement so that the distance from your hand to the top of the stick is the same as the length of your arm. For instance, if you measured 22-inches from eye to fist, grab the stick so that the 22-inch mark is at the top of your fist and the 1 inch mark is straight up. It’s important that the stick is held straight up and not leaning. Facing the tree, walk back or forth until you can see its base by looking over your fist and the top of the tree by looking over the top of the yardstick. (Don’t move anything but your eyes). When to your mind’s eye the yard stick and tree are the same length, measure the distance from your feet to the tree. That distance is the tree height.
If you ever do any of this, by all means involve the kids. It might surprise them to find out that math is good for something.
Steve Roark is the area forester in Tazewell, Tennessee for the Tennessee Department of Agriculture, Forestry Division.