(Vol. XLII.

p. 328) Dare one suspect a joke?

[3] It appears to have been long known to gamblers under the name of the Martingale. There is a paper by Babbage (Trans.

of Royal Soc.

of Edinburgh, for 1823) which discusses certain points connected with it, but scarcely touches on the subject of the sections which follow.

[4] Attention will be further directed to this distinction in the chapter on Insurance and Gambling.

[5] As by Prévost in the Bibliothèque Universelle de Genève, Oct.

1829. The explanation is noted, and apparently accepted, by Quetelet (Physique Sociale, I. 171).

[6] Essay on Probabilities, p. 126.

[7] This theoretical or absolute neglect of what is very rare must not be confused with the practical neglect sometimes recommended by astronomical and other observers. A criterion, known as Chauvenet's, for indicating the limits of such rejection will be found described in Mr Merriman's Least Squares (p. 166). But this rests on the understanding that a smaller balance of error would thus result in the long run. The very rare event is deliberately rejected, not overlooked.