The Bouguer Anomaly

The Bouguer Anomaly is a contribution to the deviation from vertical caused by irregularities in the Earth's gravitional field due to variations in density. It is most noticable near mountainous regions where it can be on the order of one minute of arc. Changes in altitude also result in gravity anomalies since gravitation is a function the distance from the Earth's center. Gravity anomalies have been known for a long time.The Schiehhallion Experiment of 1774 which involved the gravitational deflection caused by a mountain in Scottland which was used in an attempt to measure the mean density of the Earth and hence the gravitational constant.