Second: Run the finger to the given range on the range-arm.
Third: The azimuth difference is read on the nearest circle that cuts the point where the finger last rests, and the range difference is read on the scale in red ink along the azimuth circle of the board. (See Fig. 77.)
Q. What is meant by muzzle velocity?
A. The number of feet per second a projectile is moving at the time it leaves the muzzle of the gun. It is also called Initial Velocity.
Q. From the following gun commanders' range-scale find the time of flight, sight elevation, and quadrant elevation for 4120 yards range.
Gun Commanders' Range-scale.
I. V. 2200. 8-inch B. L. R. Smokeless powder.
| Quadrant Elevation. | Range | Sight Elevation. | Time of Flight, | ||
| Degrees. | Minutes. | Degrees. | Minutes. | Seconds. | |
| +4 | 16 | 4100 | -1 | 3 | 6-1/5 |
| +4 | 18 | 4120 | -1 | 1 | |
| +4 | 20 | 4140 | -0 | 58 | |
| +4 | 23 | 4160 | -0 | 56 | 7-2/5 |
| +4 | 26 | 4180 | -0 | 54 | |
| +4 | 28 | 4200 | -0 | 51 | |
| +4 | 31 | 4220 | -0 | 49 | 8-2/5 |
