Fahrenheit 451

Wigton library Book Club book this month is Ray Bradbury's Fahrenheit 451. I last read it 3 decades ago. Mrs B has enjoyed the book a lot. Big ideas about free speech. The temperature is said to be the autoignition temperature for book paper. At that temperature, the air will provide enough energy to reach the activation energy for the combustion reaction. Fahrenheit is an old and slightly bonkers temperature scale. The full story is here https://en.wikipedia.org/wiki/Fahrenheit I'd always understood that Fahrenheit had simply chosen a zero point as the coldest temperature he could find, and essentially that is true - with the caveat that it needed to be repeatable. He had to be able to recreate it to calibrate more thermometers. The other fixed points were the melting/freezing point of pure water and blood temperature. All good so far - but why the odd selection of numbers? It seems it was based on the work of an earlier scientist who had chosen 7.5 for freezing water and 22.5 for body temperature. I'll try to find out why. All Fahrenheit did was multiply these by 4 to get round numbers and then adjust from 30 and 90 to 32 F and 96 F so he could easily have a doubling scale.