In order to evaluate the reliability of recent field measurements of temperature and salinity we have followed the behavior of certa in pairs of reversing thermometers through many reversals and have examined the distribution of closely spaced measurements of temperature and salinity at intermediate depths. The errors of measurement are comparable to those of the classical expeditions and are small with respect to sampling and other errors in the upper layers of the ocean. The effect of measurement errors on computed values of specific volume anomaly, of geopotential anomaly, and of geostrophic current speed was examined.