Now I have driven this stake" (pointing to the first one) "just a little to the right of the middle of the shadow, as I remember it, so that a line from the stake to the middle of the tree-trunk must be very nearly an east and west line.
The other stake I drove merely to aid me in tracing this line.

Now I will go on with my work, explaining as I go." Taking his pocket-rule he measured off twenty feet east and west from his first stake, and drove a stake at each point.
"Now," he said, "I have an east and west line, forty feet long, with a stake at each end and a stake in the middle." This is what he had: [Illustration] "A north and south line will run straight across this, at right angles, and I can draw it pretty accurately with my eye, but to be exact I have measured this line as you see.

Now I'll draw a line as nearly as I can straight across this one, and of precisely the same length." He drew and staked the second line, and this is what he had: [Illustration] "Now," he said, "if I have drawn my last line exactly at right angles with my first one, it runs north and south; and to find out whether or not I have drawn it exactly, I must measure.

If it is just right it will be precisely the same distance from the south stake to the east stake as from the south stake to the west stake; and from the east stake to the south one will be southwest, while from the west to the south will be south-east." With that Sam measured, and found that he was just a trifle out.
Readjusting his north and south stakes, he soon had his lines right.
"Now," he resumed, "I know the points of the compass, and I'll explain how you can help me.

Our course lies exactly in a line from me through that big gum tree over there to the dead sycamore beyond.