The Measurement of Gravity

Absolute measurements of gravity are needed for establishing several physical standards: relative measurements for determining the shape of the earth and in geophysical prospecting. The time variation at a given place is of interest in connection with tidal deformations and free oscillations of the earth. The techniques currently in use for making these various measurements are described, including surface-ship and airborne surveys. The sources of error in each type of measurement are discussed and the presently obtainable accuracies indicated.