Following a brief discussion of known methods of electronic amplification, this paper describes new thermocouple amplifiers using junction-type transistors, and their theoretical and practical design. The apparatus amplify a thermocouple voltage or other input signals of any impedance such that an ordinary pointer-type galvanometer or recorder can be used as indicator. The problem of temperature compensation has also been dealt with. Details of two transistor amplifiers are given as examples. In conclusion geophysical applications are mentioned.