Abstract: In making a gas pressure thermometer measuring system comprising a container for the gas, a Bourdon tube, and a capillary of no more than about 20 m which connects said container to one end of the Bourdon tube is filled with the gas to a superatmospheric pressure prevailing at the ambient temperature. The system is hermetically sealed and the free end of the Bourdon tube is connected to a temperature indicator or recorder through a transmission mechanism. According to the method of the invention, a Bourdon tube is used which has a long overall spring movement of at least 22 mm and an effective spring movement of about 11 mm, the measuring system is filled with the gas to a pressure, prevailing at ambient temperature, of at least about 5 bar, and the non-linear indication occurring as the Bourdon tube is uncoiled is compensated for by adjusting angles .alpha. and .beta..