The use of a.c. amplification of voltages produced in very thin thermocouples is proposed as a means of measuring small intensities of radiation. The theory of the proper design of such a couple is developed and a comparison of theory and experiment given. The sensitivity available is about 100 times greater than with the usual thermocouple galvanometer arrangement.

• Received 5 January 1934

DOI:https://doi.org/10.1103/PhysRev.45.635