Abstract: A method and a system for analyzing gas samples employ at least two semiconductor sensor sets, used alternately. The sensor output signals are time-differentiated. As a result of these features, the time required for analysis can be reduced considerably, especially with an uninterrupted sequence of analyses to be performed in succession.

Abstract: In order to increase the reliability of detection of gaseous contamination in containers, gas (G) from the container is subject to several different methods of analysis (54a to 54d), each of which emits differing output signal courses (I.sub.1 to I.sub.4), depending on the contaminants and their concentration. A vector of the state vector type (P.sub.GAS) is formed with the output signals (I.sub.1 to I.sub.4) as a state variable and checked to see whether it defines a permissible or an unacceptable state of contamination (56). On the basis of this examination the decision is taken whether a container is acceptably or unacceptably contamined.

Abstract: The corrected values to compensate for errors in instrumental levelling of a theodolite and similar instruments are found by determining angles of elevation and/or horizontal directions, measuring the instrumental levelling errors, and calculating the error free values of the instrument.