RAINFALL OF WESTERN PORTION OF UNITED STATES. 53 
by the cross lines in Table VII, and computing weighted means of the 
seasonal ratios, we have— 
TABLE VII (a).* 
| Candi lath | Rotel Percentages of annual rainfall. 
Groups of stations. tude of | years of ] a hs iad : | 
group. record. Spring. |Summer. Autumn. | Winter. | Sasi 
summer. 
ee | 
Eight stations in Dakota, Minnesota, and | 
INGDIOSKdicereeae ee asaceaassasewen sce os semis 45 20 | 67 29 43 19 9 | 72, 
‘Three: stations in Kansas: s2- 22 scesecee ss 38 45 38 24 41 a4 | 11 65 
Right stationsin Texas ... .<:..-...200---.--| 29 45 85 19 36 31 14 | DO. 
*In computing the several means of Table VII (a) from the seasonal means of Table VIT, the 
latter were weighted according to the lengths of the records by which they had been obtained, 
A moment’s inspection will show that the middle group is intermediate 
between the northern and southern in all its characters. ‘The spring quota 
of rainfall progressively diminishes from north to south, and so does the 
summer, while the fall and winter quotas increase. What is lost in summer 
_is gained in winter, and thereby the inequality of rainfall from season to 
season is diminished, so that a rainy season is not so well defined in Texas 
as in Dakota. What is lost in spring is gained in autumn, and thereby the 
place of the rainy season in the year is shifted In Dakota the maximum 
of rain is earlier than in Texas, and corresponds more nearly with the 
maximum of temperature. 
TaBLE VIII.—Sceasonal precipitation in the San Francisco Region. 
| | Percentages of annual rainfall. 
.| Mean an- | 
Station. Extent of | jualrain- - a a ae - | 
| record. fall. 14. " - Winter and | 
| Spring. | Summer. | Autumn.) Winter. spring, | 
| 
Y. M. | Inches. | | 
Alcatraz Island ........-2-2266s-2+seese-see- 9 5 16. 49 16 0 11 73 89 
Ari geliislandtr2s-ssn-c2 se stcessa5s sSe0s2s 511 | 1858 19 0 15 66 85 | 
Benicia Barracks ..-. 18 3 14. 90 28 af 15 56 84 | 
Nort Millersc.--- 02. 69 | 19. 00 38 0 16 46 84 
Fort Point ........-- 14 11 17. 36 21 0 13 66 87 
HVOMtere ya. --- Seon ew ann cee -Heceesececcs ssee | 12 3 15. 71 28 2 14 56 St 
SacraMmen tO seeeen ee ett secceseess|) | 18.78 | 49.24 29 1 | 14 56 85 
San Francisco; Pre 20 2 20. 29 24 2 13 61 85 | 
San Francisco ....-.--2-- 24.4 | 2149 | 24 1 4 61 85 | 
Weighted means .<-.--.--....-.2,--. | eee Pe OE eee | 25 1 14 60 85 
Total extent of record = 130 years. Mean of yearly rainfalls = 15. 90 
