CLIMATE OF THE SANTA CATALINA MOUNTAINS. 55 
Smith* has deduced two curves of altitudinal increase of rain, one 
applicable to Pima and Pinal Counties, Arizona (the counties in which 
the Santa Catalinas lie), the second to Graham and Cochise Counties. 
These curves are based on records of various lengths, chiefly from sta- 
tions located in the valleys of these mountainous counties. Smith’s 
curves are reproduced in figure 5, in which they have been brought 
half way down toward the base line in order to make them comparable 
with the curve expressing the average summer rainfall of the Santa 
Catalina Mountains for 1911, 1912, and 1913. The portion of Smith’s 
Graham-Cochise curve extending above 5,500 feet is based on a single 
short record at 6,000 feet. 
The curve of altitudinal rise of rain for 1911, 1912, and 1913 in the 
Santa Catalinas is merely a simple average of the actual readings for 
the three summers, without any attempt to correct in accordance with 
INCHES, INCHES. 
20 
T T T T T J T T q T 
1 1 L L L s i 
3,000 4,000 5,000 6,000 7,000 6000 = 9,000 3,000 4,000 5,000 6,000 7,000 8000 9,000 
Fig. 5.—Graph showing altitudinal increase of summer rainfall on the Santa Catalina Mountains 
in 1911, 1912, and 1913 (solid line) ; together with Smith’s curves for Pima and Pinal Counties, 
Arizona (dotted line), and for Cochise and Graham Counties (broken line). 
Fia. 6.—Graphs showing vertical increase of summer rainfall in the Santa Catalina Mountains in 
1911 (solid line), 1912 (broken line), and 1913 (dotted line). 
the departure of the neighboring lowland rainfall from the normal 
during these years, without the application of any rainfall formula, 
and without the smoothing of the lines. Reference to table 4 will show 
that the record for 7,000 feet is based on two years only, and the record 
for 9,000 feet on one correct summer’s reading and the reading of one 
summer in which the gauge overflowed. 
A comparison of Smith’s curves with the curve for the Santa Cata- 
linas shows the latter to have a sharper rise from 3,000 to 4,000 feet, 
and to have a relatively level stretch from 4,000 to 6,000 feet, where 
the former curves have their sharpest ascent. 
* Smith, G. E. P., loc. cit. 
