• Directly in line with the measurement mark: This means your eye should be perpendicular to the scale at the point you are reading. This minimizes parallax error, which is the apparent shift in the position of the object when viewed from different angles.
• At eye level with the scale: Ensure that your eye is at the same height as the marking on the scale to avoid reading the measurement from an angle above or below, which can also introduce parallax error.

By following these guidelines, you can ensure the most accurate reading possible.