Abstract: An apparatus for the determination of the water status of living and nonliving materials capable of measuring the vapor pressure of water in the material at thermodynamic equilibrium by matching a solution of known vapor pressure with that of the water in the material, detected by observing the thermocouple output comprising a plurality of spiral loop thermocouples, a recording means for observing the thermocouple output, switches for connecting the thermocouples to the recording means one at a time using latching relays, a pair of contacts for each relay, each contact comprised of layers of dissimilar metals so that the current flowing under a thermalvoltage at the thermocouple in proceeding through the contacts flows through a sequence of metals across the first contact and an exact reverse sequence of metals across the opposing contact.