The Fahrenheit scale

In 1714 Daniel Gabriel Fahrenheit developed a mercury thermometer.

The Fahrenheit scale was based on the freezing point of a salt water solution (0°F) and human body temperature (98.6°F).

There are mixed reports as to how the number 98.6 was used. Some say it was originally 96, but there was experimental error, others say the temperature of a sick person (Fahrenheit’s wife) was measured and thus the human body temperature was set at 100°F.