The present paper constitutes a further report on our work on methodological and palaeoclimatological questions concerning tree rings. Ring indices are related to a meteorological index defined by us, and the correlation coefficient is computed. A rain index is also defined and compared with the differences in standardized values for trees that have grown in contact with water and in dry places. For western Sweden, the yearly precipitation seems to be sufficient for the general growth of the trees. Among our results, we would also mention that spruce and aspen show quite similar yearly growths. Finally, some hints are given on the theory underlying the construction of mean curves for ring-width diagrams.