[dragontamer]

Fahrenheit was supposed to be 0 degrees for freezing, and 100 for body temperature.

It turns out that Fahrenheit's reference thermometer was a bit... off... however.

[gumby]

Interestingly, Fahrenheit has 180 (212-32) degrees between freezing and boiling. Zero is set to a brine solution -- a reproducible metric about as cold as you could make. So it's not an insane system.

[MarkPNeyer]

0 was the coldest temperature he could reliably reproduce - which is salt water just above the freezing point.

[pyre]

How did it manage to be off by 32 (!) for freezing, but fairly close for body temperature? I would expect a constant (or at least same ballpark) error.

I imagine it had something to do with the medium used for the thermometer?

[stephenhuey]

He was trying to find a salt mixture that went through a phase change at 0 degrees:

http://antoine.frostburg.edu/chem/senese/101/solutions/faq/z...

That wasn't so reliable, and neither was using 100 for human body temperature, so when he discovered that water boiled at 212 he began calibrating with that.