June 15,1925 Environment and Chemical Composition of Grape Juices 1161 
months, 1919 is first of the five years 
during which sampling of the crop was 
carried on. 
Climatic Record for 1920 
The unusually cold weather of 
December, 1919, continued through 
January, 1920, but abated somewhat 
in February. The spring months were 
slightly above normal, July almost 3° 
below normal, and all the subsequent 
months of the year 1 to 5° above the 
50-year average (fig. 6). The last 
killing frost of the spring occurred 
May 6, but the damage done to grapes 
which presents the data for six years, 
1918-1923, for the period March- 
September, inclusive. 11 The number of 
clear days reported for this period in 
1918 and 1919 was 141 and 134, 
respectively, as against 110 for 1920 
(fig. 7), or, expressed as percentages of 
the total number of days in the period, 
the clear days were 65.8, 62.6, and 
51.26 per cent of the possible for the 
three years 1918, 1919, and 1920. The 
differences between 1919 and 1920 are 
great enough to be of considerable sig¬ 
nificance in determining the amount 
of photosvnthetic activity for the 
season. To arrive at any accurate 
Inches 
8 
[] Clear Days || Partly Cloudy Days || Cloudy Days | Days of Rain 
Fig. 5.—Rainfall and sunshine at Vineland, N. J., in 1919, with 50-year average for comparison. (All days 
showing a trace, 0.1 inch or less, are included. Some inconsistencies will be noted in the graph, the days 
of rain plus the number of clear days in some instances exceeding by one or two the number of days in the 
month. In some instances this is due to incompleteness of the Vineland records, necessitating substitu¬ 
tion of data from the nearest station; in others to inconsistency in the Vineland records themselves as, 
days on which a trace of rain fell were reported as being clear) 
was very slight. The rainfall for the 
year was 0.44 inch less than normal— 
but was abnormal in distribution—- 
the winter and early spring months 
having a little less than usual, with 
an excess of 4 inches in June, a defi¬ 
ciency of 80 per cent in October, and 
an excess in November and December. 
It is evident from inspection of Figure 
7, in comparison with Figures 3 and 5, 
that the percentage of sunshine in the 
growing months of 1920 was consider¬ 
ably less than that for the same period 
in 1918 and 1919. Such comparison is 
facilitated by reference to Table VI, 
comparison however, the days recorded 
as partly cloudy must also be evalu¬ 
ated. The term “ partly cloudy,” 
as used in the weather reports, is 
applied to any day which has 40 to 70 
per cent of its possible sunshine 
prevented by clouds. For comparative 
purposes, some value must be assigned 
to these days, as soon as photosyn¬ 
thetic activity occurred thereon. If 
we arbitrarily assume that where large 
numbers are concerned, partly cloudy 
days have on the average 50 per cent 
of sunshine, and add to the number of 
clear days one-half the number of 
ii This period is chosen for comparative purposes for the reason that grape harvest is well advanced 
and often practically complete by the end of September, only a few late maturing varieties remaining 
to be gathered after October 1 in normal seasons. 
