| The diameter of a circle | = | p | = | p |
| π | 3.14 |
| The radius of a circle | = | p | = | p |
| 2π | 6.28 |
| The surface of a sphere = 4πr² = πd² |
| The volume of a sphere | = | 4 | πr³ | = | 1 | πd³ |
| 3 | 6 |
APPENDIX B
THE METRIC OR DECIMAL SYSTEM
The metric system is a French system of weights and measures much used in the arts and sciences in every civilized country and as each unit is multiplied or divided by 10 to obtain ascending or descending values it is much more convenient to use than the older English system of arbitrary measures.
The metric system is based on the meter, which is one-ten millionth of the distance from the Earth’s equator to the North Pole. There are five units, the four latter being derived from the meter and these are:
1. The meter which is the unit of length and is about 3.280 feet in length.