  Deep-inelastic ep scattering data, taken with the H1 detector at HERA, are
used to study the event shape variables thrust, jet broadening, jet mass, C
parameter and two kinds of differential two-jet rate. The data cover a large
range of the four-momentum transfer Q, which is considered to be the relevant
energy scale, between 7 GeV and 100 GeV. The Q dependences of the mean values
are compared with second order calculations of perturbative QCD applying power
law corrections proportional to 1/Q^p to account for hadronization effects. The
concept of power corrections is investigated by fitting simultaneously a
non-perturbative parameter alpha_p and the strong coupling constant alpha_s.
