It makes more sense for the former unfortunately.
The original theory was that it could have been a pregnant women looking down and that's what lead to the proportions. The idea was they wouldn't have been able to see themselves in a river or something. But rivers and puddles, not to mention OTHER pregnant women, were extremely common so it's less likely.
You do the exact same but use 32 degrees instead of zero. I know celsius is cool and good but most people seem incapable of understanding how its just fucking marks on a line and any non-sciencey advantage is pretty much null.