  Compton scattering by the proton has been measured over a wide range covering
photon energies 250 MeV < E_\gamma < 800 MeV and photon scattering angles 30^0
< \theta^{lab}_\gamma < 150^0, using the tagged-photon facility at MAMI (Mainz)
and the large-acceptance arrangement LARA. The data are in good agreement with
the dispersion theory based on the SAID-SM99K parameterization of photo-meson
amplitudes. From the subset of data between 280 and 360 MeV the resonance
pion-photoproduction amplitudes were evaluated leading to the multipole E2/M1
ratio EMR(340 MeV) =(-1.6 \pm 0.4(stat+syst) \pm 0.2(model)%. From all data
below 455 MeV the proton's backward spin polarizability was determined to be
\gamma_\pi=(-37.9 \pm 0.6(stat+syst) \pm 3.5(model))x10^{-4}fm^4.
