Summer in Different Regions. 21 
lands of South America, where they enjoy a mean temperature 
of 62.6° to 66.2° Fahr., because these climates are characterized 
by a constancy of temperature, never rising to the higher heats 
necessary to the process of sugar forming, and the vine grows, 
and flourishes, but the grapes never become thoroughly ripe. 
Boussingault shows that, in addition to a summer and autumn 
sufficiently hot, it is indispensable that at a given period—that 
which follows the appearance of the seeds—there should be a 
month the mean temperature of which does not fall blow 66.2° 
Tahr. As will appear presently, this temperature test should no: 
be taken alone, but it will serve as a standard to show one fea- 
ture of the horticultural adaptation of the California climate. 
Boussingault claims the need of 66.2° Fahr. for a single month. 
To be sure to include this, the following table gives the average 
summer temperature at the leading fruit-growing centers 
named :— 
AVERAGE SUMMER TEMPERATURE AT VARIOUS CALIFORNIA POINTS. 
ein Pha Interior Valleys. nee Foot-hills. aaa Pes. 
Upper Lake.....| 86.9 |Redding.......... 1,363 | 74.6 
Napa -seics cs ..| 69.6 |Oroville...... = 2,421 | 76 
Livermore........ 70.8 |Marysville........ 2,500 | 85 
San Jose.......... 66.2 |Sacramento...... ; 1,290 | 82.8 
Hollister ......... 67:7. (Merced: ccsacseses 78.4 |Fall Brook.......| 700 | 68.2 
Santa Barbara..| 65.9 
Los Angeles.....| 69.7 
San Diego........ 68.4 
These points are selected because the European varieties of 
the grape reach perfection in the vicinity. Boussingault’s meas- 
ure of fitness would condemn points directly on the coast where 
the summer temperature is approximately that of San Francisco 
(59.4°), and it has been found by experience that such a sum- 
mer temperature really does not favor the ripening of the grape, 
although early varieties may mature in sheltered places. The 
excess of heat above that required, as is found at all the interior 
peints mentioned in the table, results in a very high sugar per- 
centage in the grapes, and contributes to the ripening of a sec- 
ond and third crop, as will be noted presently. The superior 
length of the growing season in California, of course, is an im- 
portant agency toward the same end. 
DIRECT SUNLIGHT ALISO A REQUISITE. 
Count de Gasparin was first to point out that not alone 
sufficient heat but abundance of continuous sunshine is a requi- 
