[Footnote 1:] Page's Philosophy of Geology, p. 38.
[Footnote 2:] Crux in this phrase means a cross erected at the parting of ways, with arms to tell whither each way leads.
[Footnote 3:] Discourse, § 218.
[Footnote 4:] Causas rerum naturalium non plures admitti debere quam quæ et veriæ sint et carum phenomenis explicandis sufficiant.
[Footnote 5:] See Prof. Fowler on the Conditions of Hypotheses, Inductive Logic, pp. 100-115.
Chapter VIII.
SUPPLEMENTARY METHODS OF INVESTIGATION.
I.—The Maintenance of Averages.—Supplement to the Method of Difference.
A certain amount of law obtains among events that are usually spoken of as matters of chance or accident in the individual case. Every kind of accident recurs with a certain uniformity. If we take a succession of periods, and divide the total number of any kind of event by the number of periods, we get what is called the average for that period: and it is observed that such averages are maintained from period to period. Over a series of years there is a fixed proportion between good harvests and bad, between wet days and dry: every year nearly the same number of suicides takes place, the same number of crimes, of accidents to life and limb, even of suicides, crimes, or injuries by particular means: every year in a town nearly the same number of children stray from their parents and are restored by the police: every year nearly the same number of persons post letters without putting an address on them.