The elevation or depression, which depends upon the charge, the distance, and the position of the object above or below the battery, must be ascertained from tables or by experiment, and the proper degree given by means of instruments.
6. When will the object be struck by merely directing the line of metal upon it?
But in one case,—when it is at point-blank distance.
7. How must the line of metal be directed for all ranges less than the point-blank range, in order to strike it?
So as to pass below the object.
8. Give a simple rule for firing at objects within point-blank.
Add to the point-blank range the difference between it and the required range, set the scale to the elevation corresponding to this sum, as shown by tables of firing. Then aim the gun directly at the object; now apply the scale, and observe where the visual ray of the scale strikes the ground, and having noted this point, aim the gun directly at it.
9. How must the line of metal be directed for ranges greater than the point-blank range, in order to strike it?
Above it.
10. When the line of metal passes over the object, what instruments must be employed for giving the proper elevation?