In Situ Sound‐Speed Measurements aboard the French Bathyscaph ARCHIMEDE at Japan

In situ measurements using two Bureau of Standards velocimeters have been obtained on several deep dives. Preliminary results indicate an agreement with previous in situ measurements aboard Bathyscaph TRIESTE to 6000‐m depth. Sound speeds are less than Kuwahara below 6000 m. The difference becomes more negative with depth, and reaches a value of −2 m/sec at 9000 m. This is different from the pressure effect predicted by the Wilson equations. Dives will conclude early in August, and a final precision calibration will be made. It is expected that the analysis will be complete by the time of presentation.