22 Value of Clear Sunlight. 
site of perfection in fruit growth and ripening, and on his author- 
ity may be based a claim of exceptional value to the fruit grower 
in the months of cloudless skies which are characteristic of the 
California summer. 
“The solar rays,’ says Gasparin, “do not only produce heat 
but bring us light, and the effects of the heat and light rays differ 
in a very pronounced manner. Without light there is no fruc- 
tification; it is not necessary that the want of light should be 
complete that there should be a failure of fruits. In fact, dif- 
fused light alone does not suffice for the greater number of 
plants; cultivated plants will not ripen their seed without the di- 
rect rays of the sun, and the longer they are deprived of it the 
smaller the quantity which they will mature.’’* 
Again, referring to the grape, for in connection with the 
growth of this iruit the most careful researches have been made, 
Humboldt wrote: “If to give a potable wine the vine shuns the 
islands and nearly all seacoasts, even those of the West, the 
cause is not only in the moderate heat of summer upon the sea- 
shore, but it exists more in the difference which there is between 
direct and diffused light; between a clear sky, and one veiled 
with clouds.” + 
It is noticeable that at the California coast points the aver- 
age cloudiness is almost twice that of the interior valleys, while 
at the East the interior fruit regions of western New York, 
Ohio, and Michigan, have a greater average cloudiness than the 
Hudson River, New Jersey, and Delaware regions near the 
Atlantic seaboard. The average cloudiness in the Eastern fruit 
regions is rather more than twice as great as in the regions of 
California where most fruit is grown. 
This excess of advantage, as it may be termed, in connec- 
tion with the high and protracted heat already mentioned, takes 
practical form in the successful ripening of a second and some- 
times a third crop of these grapes in a season, from later bloom 
on younger cane growth. Another indication of excess of advan- 
tage in the interior valley is found in the development of high 
sugar contents, which is of direct value in raisin production. 
The same tendency, though perhaps of less commercial value, is 
seen in the fact that some grapes which yield a good claret wine 
nearer the coast develop too much alcohol when grown in the 
interior. ‘ 
The advantage of California over Eastern and Southern fruit 
regions in the abundance of clear sunshine is shown by the rec- 
ords of the United States Weather Bureau in the following table. 
* Cours d’Agriculture, t. II, p. 96. 
+ Cosmos, t. I, p. 349. 
