Depending on the application, the section develops or modifies instruments for deployment in the field. For example, we developed systems with data loggers or data telemetry for long-term continuous measurements of temperature and gas composition of volcanic fumaroles. Another example is the use of portable gas chromatographs and mass spectrometers to analyse fluids and gas in deep mines and in boreholes. Our OLGA system (On-Line Gas Analysis while drilling) is now a standard component of drilling projects in the International Continental Drilling Programms (IDCP).