Pounds of water evaporated by 1 lb. of fuel as follows:—
| Straw | 1·9 |
| Wood | 3·1 |
| Peat | 3·8 |
| Coke or Charcoal | 6·4 |
| Coal | 7·9 |
| Petroleum | 14·6 |
SIGNS AND SYMBOLS USED IN EXPRESSING FORMULAS.
= Sign of equality, denoting that quantities so connected are equal to one another; thus, 3 feet = 1 yard.
+ Sign of addition, signifying plus or more; thus, 4 + 3 = 7.
- Sign of subtraction, signifying minus or less; thus, 4-3 = 1.
× Sign of multiplication, signifying multiplied by or into; thus, 4 × 3 = 12.
÷ Sign of division, signifying divided by; thus, 4 ÷ 2 = 2.
{} () [] Brackets, denoting that the quantities between them are to be treated as one quantity; thus, 5 {3(4 + 2)-6(3-2) = 5 (18-6) = 60.