An electrostatic analyser for complex waves of small amplitude

The paper describes a method of harmonic analysis in which the selective properties of the quadrant electrometer are utilized. The major portion of the energy necessary for the operation of the electrometer is derived from an external circuit by means of thermionic valves and it is therefore possible to secure accurate analyses of complex waves of small amplitude, satisfactory results being obtained with a rootmean-square value of 1 volt. In the body of the paper a general description of the apparatus is given and experimental results are cited to show the degree of accuracy that may be expected, while in the Appendices a more detailed investigation is made into certain points concerning the theory of the method.