The guy who discovered the truth about tree rings

There are some science facts so ubiquitous that it takes a while to realize that, oh yes, someone actually discovered that. Anyone who went to a state park, or looked down at a freshly-sawed stump, has held their parents' hands and heard how you can tell about the life of a tree by studying its rings. Now meet the guy… » 2/15/13 5:00pm 2/15/13 5:00pm