Abstract: A tiltmeter which uses two fluids of different thermal density coefficients, each of which is contained in its own fluid system consisting of a long tube connecting two vertical reservoirs. The two systems are deployed in physical contact along their entire length so that they experience the same thermal conditions. Measurements with this instrument are made by taking separate, simultaneous readings of the difference in fluid heights and/or bottom fluid pressure between the terminal vertical reservoirs in each of the two fluid systems; these measurements, together with known density coefficients of the fluids, provide the data to correct for errors in meter readings caused by temperature/density fluctuations in the fluids and permit a precise determination of vertical displacement and tilt over the measurement path. The ruggedness and unique design of this tiltmeter allow it to make more accurate measurements of regional tilt than previous tiltmeters and with less expenditure of money and effort.