52 VEGETATION OF A DESERT MOUNTAIN RANGE. 
6,000 feet only. In 1911 a series of stations was selected at vertical 
intervals of 1,000 feet, from the base of the mountain, 3,000 feet, to 
the station at 8,000 feet, and in 1912 a station was established on 
Mount Lemmon, at 9,000 feet. These stations have been continued 
in the succeeding summers. 
The readings of the gauges have been made at irregular intervals, as 
opportunity afforded; the water has been protected from evaporation 
by the use of kerosene, and has been measured volumetrically. The 
installation of the gauges has been made each spring in time to secure 
the first of the summer rain, and the final readings have been made in 
September, closing in 1911 on the 22d to the 25th, in 1912 on the 28th 
to 30th, in 1913 on the 25th to the 27th, and in 1914 on October 10th 
to 11th. The location of the gauges at the various altitudes has been 
such as to give them comparable topographic surroundings. Each 
station is at the summit of a ridge with a commanding opening to the 
south and without nearby trees. A record of rain has also been secured 
at the Xero-Montane Garden at 5,300 feet, near the head of Soldier 
Cajion and just below the 6,000-foot station. A recapitulation of all 
the readings of mountain rainfall is given in table 4. 
TaBLe 4.—Summer Rainfall in the Santa Catalina Mountains. 
All readings cover the total precipitation of July, August, and September. Starred figures include 
some October rainfall. Figures followed by plus are incomplete, owing to the overflowing of 
gauges. 
Averages of 
Eleva- perfect records. 
tion, 1907 1908 1909 1910 1911 1912 1913 1914 tba. 
feet. : illi- | 
Inches. netera: 
3,000 |....... 6.65 O72 | ndewany 6.27 5.61 6.46 | 10.62* 7.55 192 
fh OOO: Iie ered esu'l ia aid eamee | feracartieny ei] acumen 9.45 9.77 8.59 | 14.73* | 10.63 270 
B00 fsc-3&nasans een averse] 3c 0dns'aus [eradaede 11.97 8.24 10.27 | 19.13* | 12.40 315: 7 
6,300 |....... 9.21% 10.75 | 6.05 | 12.51 | 8.67 C209) eacsete 8.88 | 226 
6,000 |....... 6.50 | 3.42 | 5.28) 11.07 | 8.68 8.73 | 22.68% | 8.05 | 204 
1,000: lace s4024|sectscoutls sans. cosens 15.86 | 14.57 |....... 27.64-++| 15.21 | 387 
7,600 | 20.92 | 20.63 | 17.91 | 11.40 | 21.30 |........].......f.... eee 18.43 468 
83000. fdsekcciece ellie ee scgoscal| aledion doc cdadvaver| Dace d-reck 19.76 | 18.18 | 27.82+] 16.47 | 418 
OOOO) besciaseG 0s |levtra-tennauii|casunalwtce [ace avovalealenaheves acs 20.93+] 10.01 | 27.17+] 10.01 254 
The only record of daily rainfall for the Santa Catalinas is one 
secured in Marshall Gulch, at 7,600 feet, from June to August 1911, 
by Professor J. G. Brown, of the University of Arizona. A comparison 
of the daily rainfall at Marshall Gulch and at 8,000 feet with that at 
the Desert Laboratory (2,663 feet) for the period of these observations 
is given in table 5. The number of rainy days on the desert was greater 
than the number on the mountain top—381 and 19 respectively—owing 
to the 16 days with only a trace of rain at the Laboratory. The total 
rainfall of the three months was 5.42 inches at the Laboratory (for 
