4. What are its advantages?
The shell having attained a great elevation, descends with great force on the object, in consequence of the constant action of the force of gravity on it.
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5. Why are mortars constructed stronger and shorter than other pieces?
Because greater resistance is required in consequence of the high elevation under which they are fired; and were they longer, the difficulty experienced in loading them would become too great.
6. Why is a mortar constructed with a chamber?
In consequence of employing various charges, some very small, it becomes necessary to use a chamber to concentrate the charge as much as possible, so that the shell may be acted on by the entire expansive force of the powder.
7. What form of chamber is given to mortars?
Usually that of a frustum of a cone. The bottom is hemispherical in the sea-coast, stone, and eprouvette mortars. In siege mortars it is a plane surface, the angles of intersection being rounded in profile by arcs of circles.
8. What is this form of chamber called?