On the general subjects of chronology: _Encycl. Britt_., Arts. _Chronology_ and _Calendar_. Manuals of Reference: ROSSE'S _Index of Dates_ (1858); Haydn's _Dictionary of Dates_ (Vincent's edition, 1866); BLAIR'S _Chronological Tables_; Woodward and Cates, _Encycl. of Chronology_ (1872). ETHNOLOGY. Ethnology is a new science. Its function is to ascertain the origin and filiation, the customs and institutions, of the various nations and tribes which make up, or have made up in the past, the human race. In tracing their relationship to one another, or their genealogy, the sources of information are mainly three,--_physical characteristics, language_, and _written memorials_ of every sort. Ethnology is a branch of Anthropology, as this is a subdivision of Zoölogy, and this, again, of Biology. Ethnography differs from Ethnology in dealing more with details of description, and less with rational exposition. RACES OF MANKIND.--Authorities differ widely from one another in their classification of races. _Prichard_ made seven, which were reduced by _Cuvier_ to three; viz., _Caucasian, Mongolian, Ethiopic. Blumenbach_ made five, and _Pickering_ eleven. It is the Caucasian variety which has been chiefly distinguished in history, and active in the building-up of civilization. None of the numerous schemes of division, from a zoölogical point of view, however, are satisfactory. _Huxley_ has proposed a fourfold classification: 1. The Australoid, represented by the Australians and the indigenous tribes of Southern India. 2. The Negroid. 3. The Mongoloid. 4. The Xanthochroi, or fair whites, among whom are comprised most of the inhabitants of Northern Europe. To these are added a fifth variety, the Melanochroi, to which belong a part of the Celts, the Spaniards, Greeks, Arabs, etc. Of the various methods of race-division, _A. van Humboldt_ says: "We fail to recognize any typical sharpness of definition, or any general or well-established principle, in the division of these groups. The extremes of form and color are certainly separated, but without regard to the races which can not be included in any of these classes." (_Cosmos_, i. 365.) For example, black skin, woolly hair, and a negro-like cast of countenance, are not necessarily connected together. MONOGENISM.--Zoölogists, from the point of view of their own science, now more generally favor the _monogenist_ doctrine, which traces mankind to a single pair, than the polygenist, which assumed different centers of origin. The present tendencies of natural science, especially since Darwin, are favorable to the monogenist view.