4. Note on the Compressibility of Water

Extract

To test by an independent process the accuracy of the unit of my pressure gauge, on which the estimated corrections for the “Challenger” deep-sea thermometers depend, it was arranged that H.M.S. “Triton” should visit during the autumn a region in which soundings of at least a mile and a half could be had. A set of manometers, filled with pure water, and recording by the washing away of part of a very thin film of silver, were employed. They were all previously tested, up to about 2½ tons weight per square inch, in my large apparatus. As I was otherwise engaged, Professor Chrystal and Mr Murray kindly undertook the deep-sea observations; and I have recently begun the work of reducing them.