The Celsius scale initially defined as the freezing point of water and as the melting point of ice, is now officially a derived scale, defined in relation to the Kelvin temperature scale. This is the scale used in most countries in the world. This scale was proposed by Anders Celsius to the Royal Swedish Academy of Sciences in 1742. In this document it was stipulated that 0°C would correspond to the boiling temperature of the water and 100°C to the melting temperature of the ice. It was not until later that these values were reversed. Initially, the degrees of the Celsius scale were denominated degrees centigrade, only in 1948 and that they happened to have the official designation of degrees Celsius.
The Fahrenheit scale is a thermodynamic temperature scale, where the freezing point of water is 32°F and the boiling point is 212°F. This puts the water boiling and freezing points separated by exactly 180 degrees. This temperature scale was proposed by Gabriel Daniel Fahrenheit in 1724. To reach these values, he placed a thermometer inside a mixture of water and other chemical components. In the position marked by the level of the mercury inside the thermometer, Fahrenheit marked the zero point, then used the same thermometer to measure the temperature of the human body and thus marked the 100 point. Finally, he divided the space between zero and hundred in 100 equal parts. The Fahrenheit scale was born.