It looks like a small single long spring trap; it was probably set for small varmints by some young person that hadn't had much training in setting traps. In the 60's it was a common practice for people looking to trap cats to hang a rabbit and set a trap or two under it. They caught all kinds of things that weren't wanted, it takes time and learning no to catch skunks and badgers or other unwanted catches. that's where having an older experienced trapper comes in handy to teach the younger people good techniques and practices.