By Movement Or Acceleration Due To Gravity [g04f 1/04] Patents (Class 968/804)

By flowing away of a prefixed quantity of fine granular or liquid materials, e.g., sand-glass, water-clock, etc. [g04f 1/06] (Class 968/805)

By a body falling a prefixed distance in air or in a viscous material [g04f 1/08] (Class 968/808)

There are no patents to show for this class.