We started wondering what steam pipes do and what causes them to explode so I turned to Kate Ascher's great book The Works: Anatomy of a City. It has a section on steam pipes and how they heat midtown buildings with wonderful illustrations. Sadly they aren't online on Amazon but you can read about the book andsee the table of contents. I think the explosion was caused by something called a>water hammer which she explains but the on it too. The book is one of my favorites. It reminds me of the David Macaulay books I had growing up. In fact a close relation of The Works is his book, Underground. Ascher covers so much more than what is under our feet though, spans of bridges, airports and pretty much every other system the city has. During the next blackout I look forward to lighting a candle and reading about why I'm in the dark.