| 
’ 
J. D. Everett on Reducing Observations of Temperature. 177 
and cold halves of the year” in the definitions of HE, in my | 
former article. 
We will now proceed to test our determinations of range and 
date by the Greenwich table. 
The range, as measured by the difference between the warm- 
est and coldest halves of the year, is by our theory equal to 
A, X1:2879=12'44 x 1:2879=16-05. This is in error by about 
07, the warmest 182 days, April 22—Oct. 30, having a mean 
temperature of 57:00, and the coldest 183 days, Oct. 31—April 
21, a mean temperature of 40°88, showing a difference of 16°12. 
As regards date, the value of HK, is 262° 31’ or 82° 31’, ac- 
cording as we make A, positive or negative. Subtracting 15° 
from the latter, to reduce to the beginning of the year, we have 
for remainder 67° 31’, the complement of which is 22° 29’, equiv- 
alent to 22 8 days; and halfa year or 182°5 days, added to this, 
gives 205°3 days. The 22d and 205th days of the year are Jan- 
uary 22 and July 24; hence, by our theory, January 22°8 and 
July 24:3 should divide the year into halves whose mean tem- 
peratures are equal to each other and to the mean annual tem- 
perature. 
From the Greenwich table we derive the following half-yearly 
means :— 
Jan. 23—July 23, both inclusive, 182 days, mean temp. 49:0 
23 24 183 49'2 
22 22 182 _ 48:8 
22 23 : 183 48-9 
the mean annual temperature being 48-9. Hence our determina- 
tion of date is only 1 day in error. - 
The centres of the warmest and coldest halves, as already — 
stated, cannot be determined with so much precision. In the 
present case, the coldest 183 days are October 21—April 21, the 
centre of which is January 20, whereas our theory makes it 
January 22°8, 
etober 21; and the dates midway between these are January 
23°5 and July 25, which agree closely with January 22°8 and 
July 24:3. Ibelieve this agreement will be generally found to 
exist, because the term ¢, is changing its value with nearly 
maximum rapidity at the dates of intersection, and thus over- 
powers the other terms, especially as ¢,, the most considerable of 
hem, cannot hasten or retard one of the intersections to an 
_ ¢onsiderable extent, without. producing an opposite and nearly 
_ €qual effect upon the other. 
4 Am. Jour. Sct.—Szconp Szxtes, Vor. XXXVI, No. 107.—Sepr., 1963, 
4 23 
