The thermometers used by the nurse in cookery, in regulating the heat of the room or in taking the patient's temperatures are chiefly of the Fahrenheit scale. Scientists employ the Centigrade scale in most countries. While thermometers are made with both scales, it is a simple matter to translate the ordinary Fahrenheit to Centigrade.

The freezing point of the latter is 0°, while that of the former is 32° above 0.

The boiling point of the latter is 100°, while that of the former is 212°.

Hence, to change Fahrenheit to Centigrade, we subtract 32° from 212° in order that the freezing points correspond, which leaves 180° F. = 100° C. A degree Centigrade is therefore 5/9 of a degree Fahrenheit.

To change Centigrade to Fahrenheit, every Fahrenheit degree is 9/5 times as large as a Centigrade degree. It is also necessary to add 32° to the result.

Examples: Change 212° Fahrenheit to Centigrade. 212° - 32°= 180° X 5-9 = 100° C. Change 100° Centrigrade to Fahrenheit. 100° X 9-5 = 180° + 32° = 212° F.