Abstract: There is disclosed a hydrostatic leveling system including a pair of indicator heads connected by a liquid hose for equilizing static pressure in the liquid mercury pools of the indicator heads and a gas hose for equalizing the gas or vapor pressure within the heads above the pools of mercury. Each head is a float connected to the stem of a precision measuring gauge with graduations on the order of ten-thousandths of an inch. The indicator heads have identical structures and thus when they are resting on a level surface they may be reversed in location without change in gauge indicator reading; any difference in the reading is a measure of out-of-level condition. The space for the pool is sealed with a very flexible diaphragm between the float and the wall of the pool cavity. A plunger in the cavity is operated by a solenoid in the cavity to periodically thump the float to reduce tendency to stick due to surface tension, friction and hysteresis.