INTERPRETATION OF THE CURVE OF THE SEQUOIA. 159 



inches, instead of from 5 to 20 as in the preceding places, the same scale is employed for 

 purposes of comparison. The cm-ve for San Francisco is the most important, since it 

 goes back with a good degree of accuracy to 1849-50. Below the San Francisco curve 

 comes a closely similar one, showing the average rainfall for San Francisco itself, together 

 with Stockton to the east of it in the Great Valley, and Monterey and Santa Barbara, which 

 lie respectively 100 miles and 275 miles down the coast from San Francisco. These four 

 places were selected simply because they possess meteorological records going back farther 

 than those of any other towns in this region. Among the last three curves, the one for 

 Milo, at an altitude of 1,600 feet in Tulare County, between Portersville and Dillonwood, has 

 been selected not only because it is a mountain station, but because it is the nearest to 

 Dillonwood. Unfortunately this record is very short. The other two curves, for Moke- 

 lumne Hill, at an altitude of 1,550 feet in Calaveras County, and for Crocker's, at an altitude 

 of 4,450 feet in Tuolumne County, have been selected because, although these two places 

 are respectively 100 and 150 miles northwest of Hume, they are almost the only available 

 examples of the abundant precipitation which characterizes the mountainous regions in the 

 vicinity of the great sequoia groves. All of them he lower and have probably less rainfall 

 than the habitat of the sequoias, but the conditions at Crocker's appear to be closely similar 

 to those where most of the Big Trees are found. 



Inspection of the eleven cm-ves of annual rainfall in figure 40 shows that they agree 

 closely as to their main features. The years 1868, 1872, 1874, 1876, 1878, 1884, 1886, 1890, 

 and 1895 show maxima in every cm've. The maximum of 1897 appears in all the curves 

 except that for Stockton and that for 1901 in all except Bakersfield. Either 1880 or 1881 

 shows a maximum in every case, and both years are always above the average. Finally, 

 either 1906 or 1907 shows a maximum in each curve. The minima agree quite as markedly 

 as the maxima. In fact the aimual distribution of rainfall in any of the less extreme places 

 in central Cahfornia may be taken as typical of the whole region. Thus a long record, such 

 as that of San Francisco, may be used to give an approximate record for any other place, 

 simply by multiplying the San Francisco values by a sum sufficient to change the mean 

 value of the San Francisco record to the mean value of the other record for the same period 

 of time. This process of "making up" records is in common use among meteorologists. 



I am indebted to Professor Alexander G. McAdie, of the local Weather Bm-eau at San 

 Francisco, for having made up a record for Fresno by comparison with San Francisco. 

 The factor in this case is 0.47. In the comparisons of rainfall and tree growth that follow 

 I have used this made-up record for Fresno for the period from 1850 to 1882, and the 

 actual record from 1882 onward. I shall not refer to this matter again, but shall simply 

 treat the combined made-up and actual records as if they were of equal value. The 

 agreement between variations in rainfall from place to place apphes not merely to the 

 annual rainfall but also to that by months, although not to so great an extent. This is 

 evident from figure 41, where the monthly distribution of precipitation for the 8 years 

 beginning with 1889-90 and ending with 1896-97 has been plotted for Portersville, Fresno, 

 and San Francisco. Inasmuch as the rainfall of San Francisco is more than double that 

 of the other two places, it has been plotted on half as large a scale. Apart from what may 

 be called accidental details, the general form of the three cm-ves is similar, and the three 

 curves for any one year resemble one another more than do the curves for any given place 

 for three successive years. On the basis of the agreement here shown, it seems permis- 

 sible to use the San Francisco record as the basis for a made-up record of monthly as well as 

 annual rainfall for Fresno prior to 1882. I shall do this when we come to a discussion of 

 the type of seasonal distribution of precipitation which most stimulates the growth of trees. 



The actual comparison of the rate of growth of trees with the precipitation for the 

 season begirming in July of the preceding year and ending in July of the year of growth is 

 at first sight inconclusive and puzzling. Let us examine the matter in two separate cases. 



