Water Hammer (2 comments)
With some nagging from Mel and the help of the internet, I tracked down and fixed the source of the shuddering sounds we heard after flushing the upstairs toilets. The phenomenon is known as water hammer and is caused by a valve being closed abruptly. The water in the pipe which had been racing ahead a moment before displaces its kinetic energy through a series of shock waves, which rattle the pipe and can cause dangerous pressure levels. Scary as it sounds, it went away when we shut off the house's main feed and drained the affected plumbing. When they refilled, the air cushion was restored, so the water has something to compress when it's cut off abruptly. It's not permanent, though. If the air cushion got waterlogged before, chances are that it'll happen again. The determining factor for whether or not we take more drastic (read: effective and long-term) measures will be how long the problem takes to resurface.
Completely off-topic, I read today about Renault's 1993 F1 microvan. Why wasn't I told about the existence of a tiny van that topped out at 194 MPH and did 0-60 in 2.8 seconds?
After some reading yesterday, I'm impressed with the cleverness behind Dolby Pro Logic. While it shouldn't be confused for a true multi-channel approach, it's an impressive hack.