Abstract: An auxiliary force-applying mechanism is connected to a counter type altimeter for applying a supplemental force to rotate its counter mechanism at the time a Geneva type mechanism advances a second drum by one indicator position. The force applied to the drum mechanism is approximately equal to the additional force required to advance the second drum through the Geneva mechanism so that a relatively constant load is applied to the altimeter driving mechanism such as an aneroid capsule. In a second embodiment, a constant auxiliary force is applied to the altimeter drum and this relatively constant auxiliary force is relieved during the time that the Geneva mechanism advances a second drum by one drum position so that a relatively constant force is applied to the aneroid capsule.