| 968 / | HD | HOROLOGY |
| 217 | DD | INDICATING BY ACOUSTIC MEANS (at preselected times subclass 229; by electroacoustic means or electroacoustic time indicating subclass 582; time indicating by means other than acoustically, or combined means subclass 243; time indicating by visual means subclass 139; acoustic signalling arrangements G08B 3/00) [G04B 21/00] {2} |
| 218 | | .~ Periodical acoustic signalling arrangements (subclass 219 takes precedence); (adjustment of the frequency by setting the length of the pendulum subclass 115) [G04B 21/00B] |