A technique to calibrate a mercury glass thermometer and a thermostated bath (viscometry bath) using a Platinum Resistance Thermometer and a Stabaumatic Potentiometer, has been developed. The method is based on the measurement of potential difference across the thermometer at a particular temperature under a known current supplied from a standard resistor. The study was carried out over the nominal temperature range 25-35 °C. A plot between Hg/Glass temperature against bath temperature was a straight line showing a good linear Co-relation over the temperature range studies.