See Horsley, Philosophical Transactions, 1772; vol. lxii. p. 327. Montucla, Histoire des Mathematiques, vol. i. p. 239. Penny Cyclopædia, article “Eratosthenes.”

Euclid, Book x. Prop. 117.

Philosophical Magazine, December 1852; Fourth Series, vol. iv. p. 435, “On Indirect Demonstration.”

Philosophical Magazine, Dec. 1852; p. 437.

Mind; a Quarterly Review of Psychology and Philosophy; October, 1876, vol. i. p. 487.

Whewell, History of the Inductive Sciences, vol. i. p. 222.

Formal Logic, p. 124. As Professor Croom Robertson has pointed out to me, the second and third premises may be thrown into a single proposition, D = DeBC ꖌ DEbc.