Who Invented the Fahrenheit Temperature Scale and How Was Zero Degrees Fahrenheit Determined?

Daniel Gabriel Fahrenheit, who devised the scale, wanted natural reference points, but he did not choose wisely.

Fahrenheit, an instrument maker born in Danzig in 1686, developed three different temperature scales as his knowledge of natural phenomena increased.

He chose points like the freezing temperature of water and the underarm temperature of a healthy adult male.

His last scale closely corresponds to the modern scale bearing his name.

Casting about for the coldest temperature possible for the zero point on his scale, according to historians, Fahrenheit visited Ole Romer, a fellow instrument maker in Copenhagen.

Romer had calibrated his mercury thermometer based on the coldest temperature of the winter of 1708.

Thus, Fahrenheit’s zero was nothing but a particularly cold day in Copenhagen.

If the centigrade (or Celsius) and Kelvin temperature scales are based on natural phenomena like the freezing and boiling points of water and absolute zero, what is the logical basis for the Fahrenheit scale?