| 968 / | HD | HOROLOGY |
| 831 | | APPARATUS FOR MEASURING UNKNOWN TIME INTERVALS BY MECHANICAL MEANS [G04F 7/00] {3} |
| 832 | DD | .~> By measuring the distance of fall or the final velocity of a falling body [G04F 7/02] |
| 833 | DD | .~> Using a mechanical oscillator [G04F 7/04] {2} |
| 836 | DD | .~> Means used apart from the timepiece for starting or stopping same [G04F 7/10] |