1904] SMITH—PUCCINIA ASPARAGI 27 
the levee (jig. 5). The soil is naturally full of moisture, but with 
levees, drainage, and rainless summers it may become extremely 
dry unless irrigated. Fires frequently occur in the peaty formation 
and cause serious damage. Irrigation is a simple matter in most 
cases, requiring only the placing of gates in the levee to admit and 
shut off the water. 
While this country would at first seem to be one of excessive atmos- 
pheric moisture, the reverse is true in summer. Much of the 
reclaimed land becomes extremely dry, but most important is the 
position of this region directly at the opening of the great interior 
valley of California into San Francisco Bay and the Pacific Ocean 
(see fig. 4). Through this opening, formed by the Golden Gate at 
San Francisco and the Carquinez Straits at Port Costa, there blows 
in summer the strong, steady, so-called trade wind, coming in from 
the west, passing up through the straits, and then dividing north and 
south in response to the currents caused by the extreme summer heat 
of the great interior valley. In this asparagus country there occurs 
almost every day in summer a strong, dry, west wind which rises 
early in the morning and quickly dries what little dew may have been 
formed, except in sheltered spots. This wind, therefore, is an 
important and perhaps the chief factor in the amount of dew forma- 
tion. Across the lower left corner of the triangle, where the wind 
is most constant, there is practically no dew in summer. Approach- 
ing the other two angles there is more, though much less than any 
eastern section. 
At various points on the margin of San Francisco Bay are other 
asparagus districts, most important of which is that near Milpitas, 
comprising some 600 acres. This is situated, as may be seen, in a 
Sort of pocket at the lower end of the bay, surrounded by high hills 
on both sides (fig. 6). The wind current coming in at the Golden 
Gate blows across the bay quite constantly and has a tendency to 
turn south toward Milpitas and the Santa Clara Valley below, but 
at Niles it is diverted into the interior valley through the Niles Cafion 
and Livermore Pass, which open through the hills at this point. 
Without lengthening this already extended description, it need only 
be said that this produces a condition at Milpitas much similar to 
that in the East as regards dew. Atmospheric moisture from the 
