That obtained by firing a piece at very small angles of elevation, by which means the projectile which falls on ground of ordinary firmness at an angle not greater than 10°, or upon water at 4° or 5°, will make one or more bounds. In this case the projectile is said to _ricochet_. 2. What is the object of ricochet firing? To enfilade a face of the enemy’s work, which is effected by causing a projectile to bound along the terreplein of the face with the view of annoying his cannoneers, and dismounting his pieces. It is employed also in harassing an enemy, when formed or in the act of forming behind a rising ground or other obstacle, taking post in a wood, &c.; and in enfilading a line of troops. 3. What are the peculiar advantages of this fire? In being able to reach objects which cannot be reached by direct fire, on account of intervening obstacles. 4. In enfilading a face of an enemy’s work, what is the object to be fired at? Usually some point of the interior crest of the parapet which covers a flank of the terreplein to be reached. 5. What is the _point of fall_? The point of the terreplein which is first struck by the projectile, after having grazed the interior crest. [Sidenote: 74]] 6. What is the _angle of fall_? It is the angle made at the point of fall by the tangent to the trajectory with a horizontal line in the plane of fire. 7. How does the angle of fall compare with that of _elevation_? It is greater. 8. Upon what do the charge and elevation depend? Upon the distance of the object from the battery; upon the difference of level between these points; the distance of the desired point of fall from the parapet; the height of the parapet, &c. 9. If the embrasure be such that the object is masked, how is the piece pointed? The _direction_ must be given, as with the mortar, by the plummet; this is held by the person who points, in such a manner as to cover both the line of metal and the object. The _elevation_ is then given by the quadrant. 10. What is the maximum angle of elevation in ricochet firing? Against troops it should seldom exceed 3° above the surface of the ground occupied by them. Against fortresses, forts, and fortified lines, it varies from 3° to 9° above the horizontal. 11. At what distance from the object should the ricochet battery be placed? Never at a greater distance than 600 yards. [Sidenote: 75]] 12. In enfilading a work, how should the ricochet firing be conducted? The projectile should be made to graze the parapet while in the descending branch of the trajectory; and this must be effected by regulating the charges and elevating or depressing the piece until the shot is seen to fall just over the interior crest of the parapet. Light charges are generally used, varying from _two-thirds_ to _one-eighth_ of the ordinary charge. 13. What pieces are best adapted for ricochet fire?