Applying the method of correlation coefficients to the annual rainfall of Sacramento and the growth of the sequoias from 1863 to 1910, we obtain the results shown in Table 3. The trees of Section A of the table grew in moderately dry locations although the soil was fairly deep, a condition which seems to be essential to sequoias. In this case, as in all the others, the rainfall is reckoned from July to June, which practically means from October to May, since there is almost no summer rain. Thus the tree growth in 1861 is compared with the rainfall of the preceding rainy season, 1860-1861, or of several preceding rainy seasons as the table indicates. +-------------------------------------------------------------------+ | TABLE 3 | | | | CORRELATION COEFFICIENTS BETWEEN RAINFALL AND | | GROWTH OF SEQUOIAS IN CALIFORNIA[26] | | | | (_r_) = _Correlation coefficient_ | | (_e_) = _Probable error_ | | (_r_/_e_) = _Ratio of coefficient to probable error_ | | | | A. SACRAMENTO RAINFALL AND GROWTH OF 18 SEQUOIAS IN DRY | | LOCATIONS, 1861-1910 | | | | (_r_) (_e_) (_r_/_e_) | | ------ ------ ----- | | 1 year of rainfall -0.059 +-0.096 0.6 | | 2 years of rainfall +0.288 +-0.090 3.2 | | 3 years of rainfall +0.570 +-0.066 8.7 | | 4 years of rainfall +0.470 +-0.076 6.2 | | | | B. SACRAMENTO RAINFALL AND GROWTH OF 112 SEQUOIAS MOSTLY IN | | MOIST LOCATIONS, 1861-1910 | | | | 3 years of rainfall +0.340 +-0.087 3.9 | | 4 years of rainfall +0.371 +-0.084 4.5 | | 5 years of rainfall +0.398 +-0.082 4.9 | | 6 years of rainfall +0.418 +-0.079 5.3 | | 7 years of rainfall +0.471 +-0.076 6.2 | | 8 years of rainfall (+0.520) +-0.071 7.3 | | 9 years of rainfall +0.575 +-0.065 8.8 | | 10 years of rainfall +0.577 +-0.065 8.8 |