through the rocks without touching any of them. Draw the line a bit longer, right into the harbour and up on the beach. Your marks must be on that line. Take this for your first mark.” She planted a twig. “That’s the stump with the cross on it. Now you find anything else that you can see over the first mark and also on the same straight line. It can be anything. There’s no need to mark it if you know it. Then when you want to come into the harbour from outside all you have to do is to keep the two marks one behind the other. So long as you do that you will be on the straight line that brings you safe through between the rocks. Even if the lake—the sea—is high, so that some of the rocks are under water, you can sail in without looking at them if you keep your two marks one behind the other.”
“ ’Um,” said Captain John.
“Hop into Amazon , and I’ll take her out and show you.”
John