I've found another discussion of this elsewhere. The story seems to be that Vernon was walking across a plank while carrying two buckets of mercury. But the fact that a gallon of mercury weighs about 113 pounds makes this a little hard to believe. It's clear he was seriously injured, and a construction accident is certainly a plausible cause, but I'm not sure I'm buying buckets of mercury thing. While mercury shows up in buildings, it's because it's inside lighting, thermostats, switches, etc. I can't find any reason to have buckets of the stuff at a worksite.

I guess they built a mercury fountain for the 1937 World's Fair in Paris, and I've read that in Islamic Spain there were reflecting pools of mercury. Mercury was also used for a frictionless surface for moving mirrors in light houses. So I guess it's not impossible that Vernon would have been carrying mercury. But it certainly seems more likely that he was carrying something less mysterious and that the story got better in the telling.

I would agree with that assessment. Vernon was not above 'embroidering' his tales in the retelling.

Maybe he was referring to Mercury Buckets, meaning the type of tin pail made by the Mercury Tool Company. They could have been carrying nails or something:

That makes more sense than buckets of mercury...
" I was carrying two Mercury buckets...." sounds exactly like something with which Vernon would have started a story!
Brilliant analysis.

Great thread