MAGNETIC DECLINATION AT IvEW OBSERVATORY, 1890 TO 1900. 
216 
§ 34. The formula was also applied to the means of the 12 monthly values for 
individual years of the inequality range from ordinary days, and to the absolute 
ranges from quiet days, ordinary days, and all days. The method of least squares 
was employed. 
Table XXVIII. gives the results found. It also gives D, the arithmetical mean of 
the differences between the observed and calculated yearly values, and E, the 
corresponding probable error. The mean difference and the probable error are also 
Table XXVIII.—Values of Constants in Wolf’s Formula, and Resulting Accuracy. 
a. 
bx 104 
(b/a) x 10 4 . 
Mean 
differences 
calculated 
and 
observed. 
D. 
Probable 
error. 
E. 
Dx 100 
Ex 100 
Mean value’ 
Range' 
Inequality range 
, all ordinary 
6-68 
441 
66 
/ 
0-18 
/ 
0-15 
2-2 
4-0 
days 
. 
quiet days . 
7-23 
571 
79 
0-44 
0-37 
4-6 
7-5 
Absolute range, < 
all ordinary 
9-48 
741 
78 
0-51 
0-43 
4-0 
6-6 
days 
all days . 
9-95 
867 
87 
0-65 
0-64 
4-8 
7-5 
expressed as percentages, the former of the mean value of the element, the latter of 
the range of the element (or difference between the greatest and least of the 
yearly values). 
In the case of the inequality range, the agreement between the observed values 
and those calculated from Wolf’s formula is remarkably close. In five out of the 
eleven years the difference between the observed and the calculated value was less 
than O'T, and the largest difference was only (y‘33. This is noteworthy, considering 
that the element varied from G’^S to 10 /- 74. In the case of the absolute ranges the 
agreement is very decidedly less good, but, absolutely considered, it is still very fair, 
especially for the ordinary days. 
The cost of measuring and tabulating the curves was defrayed in large measure by 
a grant obtained in 1904 from the Government Grant Committee. The arithmetic 
necessary for the construction of the tables was very heavy, and I have had valuable 
assistance in this direction from several members of the staff of the National Physical 
Laboratory, especially Mr. B. Francis and Mr. G. Badderly. In smoothing the 
curves and in other directions I had much assistance from Mr. T. W. Baker, the Chief 
Assistant of the Observatory Department, who had charge of the magnetic instruments 
during the whole period dealt with. Every care has been taken to secure accuracy 
in the calculations. 
PRESENTED 
10 JU111308 
