I've been taking a wilderness travel course, run by the Sierra Club. Today's lesson was in navigation, and using a compass. That, of course, means discussing declination, how to set your declination on the compass, and, of course, how to use your compass with the declination marker set.
For those of you that don't know: Magnetic North is not True North, so to find True North, you need to add/subtract a certain number of degrees from your compass reading, which is to Magnetic North. To make that easy for the mathematically challenged, some compasses have a second arrow, or a box, that you can adjust for declination, which you can use to align the needle to, instead of using the North arrow.
According to our instructor, using this adjustable needle is sometimes termed "park the sled in the shed". Needless to say, I lapsed into a barely controlled fit of giggles at the unfortunate phrase, causing one of the other instructors to just look over at me, chuckle, and shake his head.
So there you have it... the first documented moral compass.