Quote Originally Posted by Anonymouswizard View Post
EDIT: degrees fahrenheit is a terrible system, it's definition is based on rather arbitary points that are pretty much random. Compare to Celcius/Centrigrade which uses the boiling and solidifying point of a substance vitally important to human society, and Kelvin which is the same system shifted to put 0 at the theortetical minimum energy value possible in the universe. I'll agree it's not that much difference from 'lowest tempreature I can create' but at least it's easier to refind.
They are not random...totally. They are actually based off the same boiling and solidifying points as Centigrade. It was a ball stuck in water bath with a rod attached. As the water/ball warmed up it would expand the rod (originally made of copper IIRC) and move an attached roller that was fixed axially relative to the rod-and would thus rotate as the rod moved. The set up was an ice bath and boiling were produce a reading that was 180 degrees apart- opposite directions. But things got messed up when he tried for colder substances than normal ice...and here is the stupid part...instead of adjusting for negative angles based on the contraction of the rod he re-set zero to be the coldest thing he could find...salt ice which froze 32 degrees colder than pure ice. The whole 9/5th thing is exact for that reason.
So it made some sense at the time...not fully but some.