ENVIRONMENTAL AND HISTORICAL FACTORS. Q] 
here is not exactly that of the other three stations, but the discrepancy 
can not be great. ‘This local character of the showers is most marked 
in the period of the summer rains, and is not so strikingly manifest in 
the winter season. 
In table 5 are presented the soil-moisture data, in terms of percentage 
calculated on the dry weight of the soil. In the last two columns of the 
table are the precipitation data for the short periods between observations. 
TABLE 5.—Soil Movsture and Precipitation, from October 3, 1907, to April 11, 1908. 




















a Per cent of soil moisture, calculated on dry weight. a 
Precipita- 
: r . : tion since 
Date. Hill. Larrea slope., Wash. River plain. Fee ee ok 
vation, 
15 cm./30 cm./10 cm. 20 cm.|15 cm. 30 cm./15 cm./30 cm. 
cm. in. 
TQO7, OCEss 1.707 C25 1 Post Noses Sas 3.6 3.5 O83 oe Seer ae oe 
(Cte PA ae Ol ita) Pairs Pi ede ROH) 3% FAM TSO Hi OAO40.04 
Cita ee ewe Gis ee TOs e ae OR el LAR | O.62 
OL20 ap ig rr toe Prost 3.4 187.7 PTAO Vy $662 1 0.04 | 0.25 
Nove To8be er Orr gos: eG On le NAO} 8.5. lost 9.1 Ol dt 520.60 
NOVig2 7 ei oa ue Pe 752 ie Ont 6.7 2.7 etOLd 9.7 0.46.) 0318 
Decree: 18.7 | 17.6 FA 6.3 5.9 ART I TOS Paki, $0.00" O.00 
Dect a2 pai 505 Only SOU WW 92 003-5 GAM O90 18O,001C 0.00 
MB ee oe Seem ies) 8 be! eg Baler. 6:6.) 5.0 4.4 2. Fo TOA 23.7. O00 a 0.00 
19008, [ale 2. 447. Ry Oe Ea 6.4] 5.8 FY Sepp 1L-O' | 7.04 O00 |) 0100 
VARS Ror eer yeaa) 7k Sia i OT te ALO Aa 2 O55 2182857 10262 
ete elie De Oap Ler 6.9. 9,6.7 O76) 5:5.) 1O:7 SO O.12. 10.05 
Hepes rT)... TS.0 1145 ood | 8.2 Sea | A.2 |) 10:4 8.4) O00} 0,00 
Pell Ser sa Oe Ori) DIRGIRES. GAN TAO  terd-Oll26.07)/ 27.54 2278) 1.49 
Bela? Gee ae ree Pee 1452 110.7.) 8-2 1 10.0 } 16.0 10.614)50,.24 
Mares soa 27-2 NTs 9.6 | 10.9 9 he C2 °F 19.0 VEO. 0:38 Ors 
Mare foray 025i ueeorr 7.9 9.5 6.1 ATM, DAIO Ws T5248 O25 |) hO211 
Mare 22 22 10.0) m1o.s 6.9 725 5.8 4:6 $17.0.) FOs1 || 0.07 0.38 
Petit Leas ercnoey SG o3 PT LOly 5.8 | 6.8 5.1 Woe Fie. 34 26.3 | O10") 0104 
April zi hitsoF3 8.1 SATS) He6 5.3 it. OUSTO.9- | T1264) O.001) 0°60 
1For o to 10 em. depth. 3For o to 15 cm. depth. 
*For o to g cm. depth. 4For o to 20 cm. depth. 
®10 cm.(4 in.)of snow fell on this date, and the record may below. The snow re- 
mained but a few hours. 
It is unfortunate that the soil observations could not be begun before 
the end of the summer rains, at which season the soils approached their 
maximum water-content. The series of data here given is, however, 
instructive in regard to the effectiveness of the precipitation in moisten- 
ing the soil, as well as in regard to the degree of water retention exhib- 
ited by the several soil-types. 
All of the data given in tables 4 and 5 are presented graphically on 
plates 28 to 31. In the curves of soil-moisture there presented, the 
abscissas represent time and the ordinates the percentage of soil-moisture. 
Each plate represents the conditions for one type of soil. The curve 
for the greater depth is, in each case, drawn as a full line, that for the 
lesser depth as a broken one. The numbers on the curves denote the 
