Cavendish Laboratory : Maxwell's model of Gibbs's thermodynamic surface of water (1876)
Cavendish Laboratory
<p style='text-align: justify;'>Photograph of Maxwell's model of the Gibbs's thermodynamic surface for water. For more details, see P. Harman, Scientific Letters and Papers of JCM, Vol. 3, Letter 564, pp 230-233, including plates II-V. In Maxwell's plaster cast model for water of 1876, the coordinates are volume, entropy and energy. The pressure is the tangential slope of energy against volume and the temperature is the tangential slope of energy against entropy. The blue lines are lines of constant pressure and the red lines of constant temperature. The colour lines are best seen on P2019.</p>