Reviews

Abstract

This report presents the gravity results obtained with a Worden gravimeter along the track followed by the British Trans‐Antarctic Expedition from the Shackleton Base, on the Weddell Sea, to Scott Base, on the Ross Sea, via the South Pole. The gravimeter, loaned to the expedition by the University of Wisconsin, was a single dial Worden instrument having a range of about 1000 mgals and a sensitivity of 1.2600 mgals/vernier scale division. The report is particularly valuable in that it brings out the difficulties of calibrating a gravimeter adequately. Prior to going to Antarctica, the instrument was calibrated in the British Isles on a closed loop against pendulum gravity bases located at Teddington in England, and Edinburgh and Aberdeen in Scotland. The range in gravity covered was 503 mgals. The derived calibration differed by more than 3 mgals/1000 from the value determined in a similar fashion in the United States. The traverse across Antarctica embraced 192 sites. The base value adopted for the starting point at Shackleton was the preliminary value established by the University of Wisconsin on the basis of a La Coste gravimeter connection by ship from Punta Arenas, Chile, and Buenos Aires, Argentina, Instrumental drift was determined on the basis of that observed at each base stop over a 12 to 20‐hour period. The derived composite drift was then adjusted to give the best fit to control base values at Southice, the Pole Station, and Scott Base. The Southice control value was determined from a closed loop connection, as established by air, to Shackleton. The Pole and Scott Base values used were those established by the University of Wisconsin. On the basis of the reliability of these various control points, the values of gravity determined are probably reliable to about 5 mgals. No anomaly values are given because it had not been possible, as of the time of publication, to obtain reductions of the meteorological observations for the accompanying elevation values. However, the geographic position, the observed values of gravity, and the author's estimate of reliability at each station are tabulated. Despite its limitations, this work constitutes a valuable contribution to gravimetric knowledge of Antarctica, and, once elevation data are available, will provide basic data for various for various geodetic and geophysical studies of the crust and the underlying rock surface.