Chapter VIII: The Conservation of Energy

(1) (p. 267). The Forces of Inorganic Nature, a paper by Dr. Julius
Robert Mayer, Liebig's Annalen, 1842. (2) (p. 272). On the Calorific
Effects of Magneto-Electricity and the Mechanical Value of Heat, by J.
P. Joule, in Report of the British Association for the Advancement of
Science, vol. XII., p. 33.