Measurement of C-Parameter and Determinations of alpha_s from C-Parameter and Jet Broadening at PETRA Energies

e^+e^- annihilation data recorded by the JADE detector at PETRA were used to measure the C-parameter for the first time at sqrt{s}= 35 and 44 GeV. The distributions were compared to a resummed QCD calculation which recently became available for this observable. % In addition, we applied extended resummed calculations to the heavy and wide jet broadening variables, B_T and B_W, which now include a proper treatment of the quark recoil against multi-gluon emission with single-logarithmic accuracy. % We further investigated power corrections to the mean values of the observables mentioned above. In this study, we considered all available e^+e^- data between sqrt{s}= 35 and 172 GeV.