Which statement correctly describes the foresight (FS) reading?

Which statement correctly describes the foresight (FS) reading?

• A. An intermediate point between two bench marks.
• B. Reading taken on a rod held on a point whose elevation is to be determined.
• C. Elevation of the line of sight of an instrument.
• D. Reading taken on a rod held on a point of known or assumed elevation.

Answer: (B)

In leveling, a foresight reading is the reading taken on the leveling rod when it is held at the point whose elevation you want to determine. This reading, combined with the instrument height, lets you compute the unknown elevation of that next point (Elevation of next point = height of instrument minus the foresight reading). This is what distinguishes it from a backsight, which is taken on a point of known or assumed elevation to establish the instrument height, and from readings taken on intermediate points, which are used for accuracy but do not directly give the elevation of a new point. Therefore, the statement that describes a foresight reading as a reading taken on a rod held on a point whose elevation is to be determined is the best description.

In leveling, a foresight reading is the reading taken on the leveling rod when it is held at the point whose elevation you want to determine. This reading, combined with the instrument height, lets you compute the unknown elevation of that next point (Elevation of next point = height of instrument minus the foresight reading). This is what distinguishes it from a backsight, which is taken on a point of known or assumed elevation to establish the instrument height, and from readings taken on intermediate points, which are used for accuracy but do not directly give the elevation of a new point. Therefore, the statement that describes a foresight reading as a reading taken on a rod held on a point whose elevation is to be determined is the best description.