Final answer:
The FM 3-25.26 defines a bar scale as a graphical representation of a map scale, used for measuring distances on a map.
Step-by-step explanation:
The FM 3-25.26 is a Field Manual published by the Department of the Army, and it guides Map Reading and Land Navigation. In this manual, a bar scale is defined as a graphical representation of a map scale, consisting of a graduated line divided into equal parts, each of which represents a certain distance on the ground.
For example, if one centimeter on the bar scale represents one kilometer on the ground, measuring the distance between two points on the map using the bar scale can help determine the actual distance between those points in kilometers.
The bar scale is an essential tool for accurately interpreting and measuring distances on a map, providing a visual reference for understanding the scale of the map concerning the actual terrain being represented.