Fig. 5.—Comparison of the Thermometer Scales.

COMPARISON OF THERMOMETER SCALES

A little study of the accompanying information and diagram will enable any one to form a clear idea of the various thermometer scales and to convert temperatures from one scale to another.

Table of fixed points.

Scale. Temperature of
melting ice.
Temperature of
boiling water.
No. of degrees
between melting ice
and boiling water.
Centigrade 0 100 100
Reaumur 0 80 80
Fahrenheit 32 212 180

Only Fahrenheit and Centigrade scales are in general use, and the accompanying plate is designed to enable observers to convert temperature readings from one scale to the other without resorting to a mathematical formula.

For accurate and precise reductions between the different scales the following rules should be used:

1. To convert Fahrenheit to Centigrade: Subtract 32 and multiply by five ninths.

2. To convert Centigrade to Fahrenheit: Multiply by nine fifths and add 32.

3. To convert Fahrenheit to Reaumur: Subtract 32 and multiply by four ninths.

4. To convert Reaumur to Fahrenheit: Multiply by nine fourths and add 32.

5. To convert Centigrade to Reaumur: Multiply by four fifths.

6. To convert Reaumur to Centigrade: Multiply by five fourths.