TABLE,

showing the rate of inclination of inclined planes, for the following

The accurate determination of heights, and distances of objects being required in various military operations, especially for the position of batteries, the following methods for their attainment will be found useful, when the requisite instruments are at hand; by frequent practice, the eye should, however, be enabled to determine, nearly, either the height of, or distance from any object.

HEIGHTS.

1.-BY MEANS OF A 66 POCKET SEXTANT,"

to ascertain the height of an object.

When the sextant is used for taking the height of objects, it is to be held vertically, and the quicksilvered part of the horizon glass will be on the left hand of the observer, or on the left part of the transparent glass. Altitudes are measured in the same manner as horizontal angles, for if we conceive the horizontal triangle A B C (vide Plate 2, Fig. 2, page 298) to be raised on its base A C with the angle C next to the observer, then the perpendicular A B becomes the height of the object B ; and supposing the object to stand on a horizontal plane, then the ground and the object form the right angle at A; therefore, if the object is accessible, the sextant need only be set at any of the angles mentioned for distances (vide Art. DISTANCES), and walking backward on the