Before reading an aneroid barometer, what should you do to ensure the pointer is accurate?

To ensure the pointer of an aneroid barometer is accurate before taking a reading, tapping the face lightly is the appropriate action. This gentle tap helps the mechanism inside the barometer settle into its proper position, removing any small friction or sticking that might prevent the pointer from moving freely. It ensures the needle is responsive to changes in atmospheric pressure and accurately reflects the current pressure at the location.

Waiting for stabilization, while it may seem like a reasonable choice, does not address the potential for the pointer to be stuck or not functioning correctly at that moment. Rotating the casing would not impact the accuracy of the reading, as the casing should be calibrated to indicate atmospheric pressure, and aligning with a standard implies comparing it to another measurement, which is not necessary for an immediate reading.