Definition:Fahrenheit/Historical Note

Historical Note on Fahrenheit
The Fahrenheit scale is based on that proposed in $1724$ by the physicist.

He initially defined the lower reference point from the lowest temperature he could achieve, by mixing equal parts of ice and salt and establishing the temperature at which it melted.

The upper reference point, $96 \fahr$, was taken to be his best estimate of the temperature of the human body.

For scientific purposes it has been all but completely superseded by the Celsius scale.

By the end of the $20$th century, Fahrenheit was used as the official temperature scale only in the US and its unincorporated territories, the Bahamas, Belize, and the Cayman Islands.