• (n.) One versed in the phenomena of history and the laws controlling them.
His·to`ri·on'o·mer noun [ Greek ... history + ... to distribute.] One versed in the phenomena of history and the laws controlling them. « And historionomers will have measured accurately the sidereal years of races.» Lowell. 
historionomer, historionomical Someone who is versed in the principles that regulate the course of history.