updating Little Chicago

The table in the middle of the room had once been my work area. No longer. Now it was wholly occupied by Little Chicago.
Little Chicago was a scale model of Chicago itself, or at least of the heart of the town, which I'd expanded from its original design to include everything within about four miles of Burnham Harbor. Every building, every street, every tree was represented by a custom-made scale model of pewter. Each contained a tiny piece of the reality it represented - bark chipped from trees, tiny pieces of asphalt gouged from the streets, flakes of brick broken from the buildings with a hammer. The model would let me use my magic in new and interesting ways, and should enable me to find out a lot more about Grey Cloak than I would have been able to do in the past.
Or... it might blow up. You know. One of the two.
I was still a young wizard, and Little Chicago was a complex toy containing an enormous amount of magical energy. I had to work hard to keep it up-to-date, matched to the real Chicago, or it wouldn't function correctly - i.e., it would fail, possibly in a spectacular fashion. Releasing all that energy in the relatively cramped confines of the lab would most likely render me extra crispy. It was an elaborate and expensive tool, and I never would have so much as considered creating it if I didn't have an expert consultant.


White Night Chapter 14, Page 132-134