Outside my office, between the parking lot and the woods, there are a half dozen wooden picnic tables, stacked one on top of the other. They are chained together, presumably to keep any of them from wondering off (as it were). The chain is a little the worse for being out in the weather all the time. I didn’t really test it of course, and for all I know it’s still strong enough to stand up to average abuse. Nevertheless, it looks a bit weakened and a strong piece of iron inserted between the sides of a link and twisted might snap the chain quite easily.