In an offensively dismissive letter: An extract from Tait’s letter to Perry is included in Perry 1895a.

“You say I am right”: Letter of Perry to Tait on November 26, 1894. This letter is also included in Perry 1895a. Perry also noted, “I found that so many of my friends agreed with me.”

“I should like to have your”: Letter of Tait to Perry on November 27, 1894 (Cambridge University Library, Papers of Lord Kelvin, Add. MS. 7342, P59d). Included in Perry 1895a.

“It is for Lord Kelvin to prove”: Letter of Perry to Tait on November 29, 1894. Included in Perry 1895a. Perry emphasized two arguments in his letter: (1) that there was a certain amount of fluidity inside the Earth, so that heat could be transported by convection, and (2) that according to results by Robert Weber, the conductivity of rocks increased with increasing temperature. Later, the latter turned out to be wrong.

“I feel that we cannot assume”: Letter from Kelvin to Perry on December 13, 1894. Included in Perry 1895a, p. 227. Kelvin was interested in particular in checking Weber’s results on the conductivity.