Finding Captain Kidd's Treasure

Date: 05/17/2000 at 12:31:59
From: Jane Nilsson
Subject: Treasure Hunt

You are on a island and you have found a letter with the text: "Start 
at the tree. Count your steps to the white stone and then go left from 
the stone as many steps as before. Mark this place. Go back to the 
tree. Count your steps to the black stone and then go right as many 
steps as before. Mark this place too. The treasure of Captain Kidd is 
between the marked places."

You find the white and the black stone, but there is no sign of the 
tree. You still find the treasure. Show how.

Please help me.

Date: 05/18/2000 at 14:16:56
From: Doctor Schwa
Subject: Re: Treasure Hunt

Draw a careful picture with the stones shown. Make a few copies of it. 
Put the tree in a few different places (or do these drawings on a 
computer geometry system where you can drag the tree around).

What you'll find is that, after following these directions, the 
treasure is always in the same place! Doing the drawing carefully will 
help give you some clues about why the treasure ends up in the same 
place no matter where the tree is.

- Doctor Schwa, The Math Forum
  http://mathforum.org/dr.math/