3. Are the same means employed for giving mortars their direction as those which are used with guns and howitzers? No; because mortars are usually masked from the object to be struck, by an epaulment or parapet. 4. To what are all the methods employed for giving the direction to mortars reduced? To determining practically two fixed points, which shall be in line with the piece and the object, and sufficiently near to be readily distinguished by the eye. These points being covered by the plummet, determine a vertical plane, which, when including the line of metal, becomes the plane of fire. 5. What is the simplest manner of directing the mortar? By means of _pointing-wires_. [Sidenote: 57]] 6. Describe this method. The two fixed points required are determined by planting two wires upon the epaulment, one upon its crest, and the other about a yard in advance of it, both as nearly as possible in the vertical plane passing through the centre of the platform and the object. The points being thus established, the direction is given to the mortar, by causing a plummet held in rear of it, to cover the wires and the line of metal. 7. In what respects is this method defective? Both in accuracy of aim, and the liability of the wires being deranged by the shots of the enemy or by other causes. 8. Give a better method. By means of _pointing-stakes_, by which one of the fixed points is established upon the crest of the parapet, or at the toot of the interior slope, and another in rear of the piece. Then by a cord called the _pointing-cord_, stretched between these two points, with the plummet suspended from it, a vertical plane is determined with which the line of metal is made to coincide. 9. How are the stakes planted? A stake, a foot or more in length, is driven into the crest of the epaulment, as nearly as practicable in the vertical plane of fire passing through the centre of the platform; sighting by this stake, another long one is planted, three or four feet in front of it, in line with the object. To this stake the cord is temporarily attached, and stretched by the first stake, just grazing it, to a point on the ground, one yard in rear of the platform. At this point a third stake is driven. The cord is removed from the second stake, which may now be taken away, and permanently attached to the first. [Sidenote: 58]] 10. How is the mortar directed? The cord is stretched to the rear stake, and as near the muzzle-band as possible, with the left hand, while the plummet is suspended against it with the right; or the plummet may be attached to the cord, just in rear of the mortar. 11. How does it appear that the mortar is thus _properly_ directed? Because the cord, the plummet, and the line of metal, are evidently in the vertical plane of fire. 12. What is done in case the shell should strike constantly to the right or left of the object?