| = 60 × 12 × 100 × 80. |
Now each (20 × 30 × 480) square inches is area of one ream.
Output of paper per hour in reams
| = | 60 × 12 × 100 × 80 | . |
| 480 × 30 × 20 |
Output of paper per hour in lbs.
| = | 720 × 100 × 80 × 30 |
| 480 × 30 × 20 | |
| = | 600 lbs. |
The general formula may be applied for the purpose of calculating the speed at which the machine must be driven.
Example.—A machine with 75-inch deckle is required to produce 6 cwts. per hour of a paper 25 inches by 18 inches (500 sheets), weighing 19 lbs. to the ream. At what speed is the machine to be driven?
Output in lbs. per hour
| = | 720 × F × D × R |
| S × L × W | |
| 672 = | 720 × F × 75 × 19 |
| 500 × 18 × 25 | |
| F = | 148 feet per minute. |