Sometimes I find things around the house that will make a fun geocache. This is one of those caches. When you find it, you will know what is to be done to retrieve the container with the log. Remove the lid before attempting to operate the mechanism. Also, do not put your eye or any part of your body over the opening when operating. (not responsible for accidents).
Watch closely to see which direction the projectile goes so you can retrieve it, write on the log, and reload it. REMEMBER TO REPLACE THE LID!! The lid keeps debris from fouling the mechanism.
Look on the back side of the tall stump for what you seek.