[28] Pure Logic, or the Logic of Quality apart from Quantity, 1864, pp. 10, 16, 22, 29, 36, &c.
[29] Brewster, Treatise on New Philosophical Instruments, p. 273. Concerning this method see also Whewell, Philosophy of the Inductive Sciences, vol. ii. p. 355; Tomlinson, Philosophical Magazine, Fourth Series, vol. xl. p. 328; Tyndall, in Youmans’ Modern Culture, p. 16.
[30] Formal Logic, p. 38.
[31] Hallam’s Literature of Europe, First Ed., vol. ii. p. 444.
[32] Outline of a New System of Logic, London, 1827, pp. 133, &c.
[33] An Investigation of the Laws of Thought, pp. 27, &c.
[34] Formal Logic, pp. 82, 106. In his later work, The Syllabus of a New System of Logic, he discontinued the use of the sign.
[35] Principles of Psychology, Second Ed., vol. ii. pp. 54, 55.
[36] Pure Logic, or the Logic of Quality, p. 14.
[37] Pure Logic, pp. 18, 19.