See Goodwin, Cambridge Philosophical Transactions (1845), vol. viii. p. 269. O’Brien, “On Symbolical Statics,” Philosophical Magazine, 4th Series, vol. i. pp. 491, &c. See also Professor Clerk Maxwell’s delightful Manual of Elementary Science, called Matter and Motion, published by the Society for Promoting Christian Knowledge. In this admirable little work some of the most advanced results of mechanical and physical science are explained according to the method of quaternions, but with hardly any use of algebraic symbols.

Birch, History of the Royal Society, vol. iii. p. 262, quoted by Young, Works, vol. i. p. 246.

Opticks, Query 28, 3rd edit. p. 337.

Rankine, Philosophical Transactions (1856), vol. cxlvi. p. 282.

Cosmotheoros (1699), p. 16.

Laplace, System of the World, vol. ii. p. 316.

Cosmotheoros (1699), p. 17.

Ibid. p. 36.

System of the World, vol. ii. p. 326. Essai Philosophique, p. 87.

Principia, bk. ii. Section ii. Prop. x.

De Morgan, Cambridge Philosophical Transactions, vol. xi. Part ii. p. 246.