Hi Don,

I'm the one that was ranting about the arbitrariness of the Farenheight scale. You are of course correct that the celcius scale is equally arbitrary, but at least there is a known reason for it. So I was thrilled to hear your explanation but my hopes were dashed by none other than the US Navy, https://www.onr.navy.mil/Focus/ocean/water/temp3.htm "The freezing point of seawater is about 28.4&deg;F (-2&deg;C), instead of the 32&deg;F (0&deg;C) freezing point of ordinary water. " 

But then wikipedia (https://en.wikipedia.org/wiki/Daniel_Gabriel_Fahrenheit) explains "The lowest temperature was achieved by preparing a frigorific mixture of ice, water, and ammonium chloride (a salt), and waiting for it to reach equilibrium. The thermometer then was placed into the mixture and the liquid in the thermometer allowed to descend to its lowest point. The thermometer's reading there was taken as 0 &deg;F. "

Not that seems to support your point but then we have "The second reference point was selected as the reading of the thermometer when it was placed in still water when ice was just forming on the surface. This was assigned as 32 &deg;F. " - Which begs my question why pick 32 degrees for that ?

Continuing "The third calibration point, taken as 96 &deg;F, was selected as the thermometer's reading when the instrument was placed under the arm or in the mouth." So he may have been using a multiple of 32 but why ?

Also - you owe me a show :)

Ken.

