A doubly grafted thermometer composed of two thermocouples of different kinds, a transis-tor thermometer and a suitable operational amplifier is described.
The proportional constants γ and β2 of the transistor thermometer and the auxiliary thermocouple are ajusted by the operational amplifier to be equal to the proportional constant β1 of the main thermocouple, and the sum of their outputs is measured.
It is proved theoretically that the temperature to be measured is obtainable from the measured voltage even for a doubly grafted thermometer.
Experiments are carried out with two typical grafted thermometers, in one of which the main and auxiliary thermocouples are grafted thermally, and in the other they are grafted directly.
The results of experiments show that the outputs of the trial doubly grafted thermometer of both kinds agree fairly well with the e. m. f of a thermoelectric thermometer of the main thermocouple alone with the reference temperature at 0°C.
