I’m Right, To A Degree

Last weekend I was evangelising as to the superiority of the metric system over imperial. I do this a lot. While explaining how celcius is much more reasonable than fahrenheit I was met with the response that ‘fahrenheit is more accurate because there are more degrees per celcius degree’. Interesting. This bothered me. I mean, obviously you can just go down to decimal places, but I didn’t like there being a comeback that I couldn’t immediately respond to. So this evening I looked up fahrenheit, as I realised I knew next to nothing about it (why was I evangelising about something I don’t know much about? Shut up). Turns out that fahrenheit as a scale is completely nuts.

Paraphrasing the wikipedia entry: Physicist Gabriel Fahrenheit took the temperature at which an equal mixture of ice and salt melts, as well as the temperature of blood, and developed a scale between the two with twelve subdividisions. He then split each subdivision into eight, so that the two fixed points of the scale were at 0 and 96. It was later observed that plain water froze at 32 degrees and boiled at 212 degrees. He turned out to have messed up, however, and after he died the entire scale was recalibrated so that water really did freeze at 32 and boil at 212. So the temperature of blood, ie. the human body temperature, changed at this point.

So that’s pretty weird. Centigrade and celcius (which are actually the teeniest bit offset due to their differing definitions – although sources will disagree on this point) make far more sense. At the risk of being patronising, they’re better because they use units of ten and have the triple point of water at 0 and its boiling point at 100 (sorry, I just wanted to be thorough). How would one further subdivide up the fahrenheit scale? Admittedly it’s arbitrary, but there’s no obvious way to do it. Should it be broken up into twelfths? Eighths? I go nuts when I see something like “5.8 inches” – that’s basically saying ‘yes, units of ten make more sense for things we don’t know, but above that it’s perfectly reasonable to use 12/16/8/13/whatever we feel like!’. So how are you going to avoid this bizarre result with the fahrenheit scale? You’re not.

So I think that in terms of consistency, ease-of-use and logic, the celcius scale is in fact more accurate than fahrenheit as it can be subdivided in a way that makes sense. It has to be said, though, that while celcius is great, Kelvin‘s the best 🙂