  We analyse elastic-pion nucleon scattering to fourth order in heavy baryon
chiral perturbation theory, extending the third order study published in Nucl.
Phys. A640 (1998) 199. We use various partial wave analyses to pin down the
low-energy constants from data in the physical region. The S-wave scattering
lengths are consistent with recent determinations from pionic hydrogen and
deuterium. We find an improved description of the P-waves. We also discuss the
pion-nucleon sigma term and problems related to the prediction of the
subthreshold parameters.
