(a) Units of measurement: day, month, year, decade, century, administration, sovereignty, ministry, epoch, era, and the unit determined by the movement of the events themselves as they naturally cohere.

(b) Dates as agencies for assigning definite position in time.

2. Place Element: The where, or geography.

(a) Units of location: continent, nation, empire, kingdom, state, section, region, district, town, city, county, and the geographical groups or centers formed by the events themselves as they cohere.

3. Physical Element:

(a) Climate and meteorology affecting

(1) Character of the people.

(2) Occupations.

(b) Topography, affecting

(1) Movement of races, armies, productions, etc.