Control the boiler by turning the big wheel to the right of the boiler.
The green arrows increase the flame. The red arrows decrease the flame.
When the boiler is powered up with the maximum flame, the tree elevator rises.
When the tree elevator is up all the way, turn the flame down on the boiler as far as it will go. The tree elevator will start descending until at the bottom.
Go back to Myst Island -- The tree elevator.