1) Chronometry 
Horometry is the art, practice or method by which time is measured in hours or by smaller units. By this account, a `horometer` (hour + -meter) is an instrument that measures time. ...
time measurement
• (n.) The art, practice, or method of measuring time by hours and subordinate divisions.
Ho·rom'e·try noun [ Confer French horométrie . See Horometer .] The art, practice, or method of measuring time by hours and subordinate divisions. 'The horometry of antiquity.' Sir T. Browne. 
horometry The measurement of time; also, the determination of the exact error of a timepiece by observation.