After dinner (which impressed Zahn's family enough for them to urge him to propose soon to Amelia), Amy asks Zahn to help her with something. While holds the remaining branches out of the way, Amy goes into Stephan's cabin and tries to line up the slots and holes in the key-pendant with the view outside of the window. She gets a good idea of where to go, but can't see it clearly in the dimming daylight.

Zahn goes to get a night-lamp for her, and the two head out to the edge of the Wingnut territory, where the old central meeting tree used to be. Exploring the tree, the eventually reach the top where an ornate door is. Amelia uses the key on it, and gets it open. Inside is a hemispheric room with a complicated lighting device. After lighting the lamps inside, it turns out to be an astrolabe, projecting the night sky on the polished walls of the chamber. This is amazing to Amelia, who has never seen the whole sky at once, due to Sylvania's near-perpetual overcast.

Zahn goes to explore the upper chamber, and Stephan's ghost appears to talk to Amelia, saying that he hoped she'd be inspired by the place that he meant for her to use it to learn more about mechanics. The opportunity comes quickly, as part of the machine seizes up and she has to try and repair it before it breaks. During the process, Stephan possesses her just enough so that she can see how it all works.