Previous LaCoste and Romberg air-sea gravity meters have been operated in gimbals, and gravity corrections have been made for the swinging of the gimbals. Because there is reason to believe that better accuracy and operation in rougher weather might be possible with a gravity meter mounted on a gyro-stabilized platform, such a model has been made.

The gyro-stabilized platform uses inertial guidance quality gyros and is accurate to about 1 minute of arc. It appeared to be entirely adequate both for laboratory tests on motion-testing machines and for tests on a ship. The gravity meter used in the first tests was one which had been used previously with a gimbal suspension, although it was known that some modifications would be desirable for operation on a stabilized platform. The overall accuracy obtained was about the same as that of the gimbal-suspended type, and it was capable of operation at about the same accelerations as the gimbal type.

In order to be able to attain the improved performance expected from a good stabilized platform, a newly constructed air-sea gravity meter was disassembled and modified as follows:

(1) It was made several times stiffer in the horizontal directions, because operation on a stabilized platform requires greater stiffness than operation in gimbals;

(2) The linearity of response of the gravity meter to vertical accelerations was greatly improved, in order that errors would be negligible at much greater accelerations.

A device for computing errors resulting from interaction between horizontal and vertical accelerations also was added. Laboratory tests on the new model are now in progress and it is hoped that ship tests will be completed in time to report the results when giving this paper.

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