Boxing day: Margaret and William went out to the Hobbit play at the Globe. I gave Gertrud my ticket. It was really more to see George's girls than the play so I figured I would catch up with them another time, so I stayed behind. Shortly after everyone left, I noticed how chilly the house had become so I called the furnace guys again. The first thing he noted was how dirty the furnace was (didn't two guys clean in two days ago?) and the warning light told him to keep looking for trouble.. It came in the form of a cracked heat exchanger. The crack is not too terrible and the carbon monoxide levels in the house are not dangerously high, but he's warned us not to keep it on for too long and to have a detector nearby. We warmed up later at Richard and Gerda's then went home to curl up on the couch, conserve body heat, and watch tv.