In leveling, the first observation is to a known point and is termed a backsight. Which of the following is the correct designation for the first observation?

In leveling, the first observation is to a known point and is termed a backsight. Which of the following is the correct designation for the first observation?

• A. Foresight
• B. Intermediate sight
• C. Backsight
• D. Reversed sight

Answer: (C)

The main idea is that the first observation in leveling is made on a point whose elevation is known to set up the instrument. This initial reading is called a backsight because you’re looking back to a known point to establish the height of the instrument (HI). Once the HI is known, you can take readings on other points to determine their elevations. Readings on points ahead of the instrument are foresights, and readings on points between the backsight and foresight are intermediate sights. A reversed sight isn’t part of the standard leveling sequence for establishing elevations.

The main idea is that the first observation in leveling is made on a point whose elevation is known to set up the instrument. This initial reading is called a backsight because you’re looking back to a known point to establish the height of the instrument (HI). Once the HI is known, you can take readings on other points to determine their elevations. Readings on points ahead of the instrument are foresights, and readings on points between the backsight and foresight are intermediate sights. A reversed sight isn’t part of the standard leveling sequence for establishing elevations.