I just found out that my father-in-law's father (so grandfather-in-law I guess) was the inventor of the tripod jack. They were used for jacking up large planes.
It's sad that my wife inherited all the mechanical genes and I'm left with searching for every one of my mechanical questions on forums.
If you're interested, here's some info on the patent:
Here's some pics:
I was also given a home-made scissor jack made by the same man (Ralph Shroyer). I'll post a pic of it when I get the chance.
I think it's pretty cool to see where and why we use some of the tools we have now...