Stacey et al. have reported evidence for a breakdown of Newton’s law based on measurements in a deep mine. We have tested the reproducibility of this result by analyzing gravity data from boreholes in Nevada. One interpretation of our resuls suggests a breakdown of the Newtonian theory which is much larger than the effect previously reported. But the lack of consistency between the results suggests that it is not fundamental physics that has failed, but rather the experiments are subject to large systematic uncertainties which are caused by mass anomalies at intermediate distances from the holes.

• Received 26 September 1989

DOI:https://doi.org/10.1103/PhysRevLett.65.1173