FROM SELECTED DAYS DURING THE SEVEN YEARS 1898 TO 1904. 
325 
are clue are the same. I thus split the 10 days of each month into two groups, 
according to the size of the potential range, and have compared the mean results 
from the two groups of 35 days derived in this way from” the seven years. Except 
as regards the criterion by which the 10 days were subdivided, the procedure was 
exactly the same as that followed in calculating Table XIII. The results of the new 
subdivision are shown in Table XIV. 
Table XIV.—Mean Excess of Values of Meteorological Elements for Groups of Days 
of Larger as compared to Groups of Days of Smaller Potential Range. 
Potential 
range. 
Barometric 
pressure in 
inches. 
Temperature, 
Fahrenheit. 
Wind, 
miles per hour. 
i Sunshine, 
hours per day. 
January. 
116 
+ 0-194 
o 
- 2-14 
- 1-39 
4- 0 * 54 
February .... 
104 
+ 0-027 
- 2-35 
- 1-35 
+ 1-15 
March. 
113 
+ 0-012 
-2-33 
- 1-74 
+ 1-23 
April. 
87 
+ 0-036 
-2-78 
-2-74 
-0-41 
May. 
83 
-0-072 
-3-98 
+ 0-33 
- 1-27 
J une. 
66 
-0-048 
o-oo 
+ 2-30 
+ 0-05 
July. 
71 
-0-022 
+ 2-22 
+ 0-02 
+ 2-12 
August. 
62 
0-000 
-0-29 
- 1-02 
-0-37 
September .... 
57 
+ 0-001 
- 1-59 
-0-30 
-0-61 
October. 
117 
-0-013 
- 1-93 
+ 1-13 
+ 0-50 
November .... 
113 
+ 0-094 
-3-58 
- 1-71 
-0-21 
December .... 
113 
+ 0-150 
-3-88 
-0-08 
+ 0-14 
Year. 
92 
+ 0-030 
- 1-89 
-0-55 
+ 0-24 
Winter. 
112 
+ 0-116 
-2-99 
-1-13 
+ 0-40 
Equinox .... 
94 
+ 0-009 
-2-16 
-0-91 
+ 0-18 
Summer .... 
70 
-0-035 
-0-51 
+ 0-41 
+ 0-13 
Comparing Tables XIII. and XIV., we find that the signs of the meteorological 
differences agree in the large majority of instances. The meteorological conditions 
which are associated with high potential thus appear associated with a large diurnal 
raDge. The phenomenon may mean nothing more than that the size of the daily 
range tends ceteris paribus to increase or diminish according as the mean value of P 
is greater or less. The association, however, with low temperature, low wind velocity, 
and long sunshine, seems decidedly less in Table XIV. than in Table XIII. There is 
considerably greater regularity in the results for barometric pressure in Table XIV. 
than Table XIII., but the relationship with P seems decidedly opposite in summer to 
what it is in winter. The natural inference is that there is little if any direct 
connection between the absolute height of the barometer and the size of either the 
daily mean or the irregular daily range of P. On the other hand, in winter it seems 
clear that the weather conditions which accompany a high barometer favour the 
existence of high values and big diurnal changes in P. 
