Robert T. Beyer
Dept. of Phys., Brown Univ., Providence, RI 01912
In the 1880s, the Scottish physicist P. G. Tait set up an empirical equation to fit pressure-volume data for fresh and salt water, gathered on a research expedition of the H. M. S. Challenger [``Physics and Chemistry'' of the Voyage of H. M. S. Challenger, Vol. II, part IV (1888)]. This equation, together with two or three variants of it, was the starting point of a number of researches over the next 70 years. In the 1950s, it was put to use in still another form, and became the ancestor of the quadratic relationship of pressure and density used in nonlinear acoustics. The history of this development and the connection between the Tait equation and the ratio B/A is set forth.