Grove, Correlation of Physical Forces, 3rd edit. p. 118.

Ibid. pp. 166, 199, &c.

Philosophical Transactions, 1861. Chemical and Physical Researches, p. 598.

Life of Sir W. Hamilton, p. 439.

Powell’s History of Natural Philosophy, p. 201. Novum Organum, bk. ii. Aphorisms 5–7.

Thomson and Tait, Treatise on Natural Philosophy, vol. i. pp. 346–351.

Philosophical Transactions (1740), vol. xli. p. 454.

Principia, bk. i. Law iii. Corollary 6.

Helmholtz, Taylor’s Scientific Memoirs (1853), vol. vi. p. 118.

Lucretius, bk. i. lines 232–264.