478 TABLE 503.— HOURLY DEPARTURE OF MAGNETIC DECLINATION 



FROM NORMAL* 



The daily variation is not predictable in detail since it fluctuates in form and amplitude from 

 day to day. However, the variations shown in this table appear with considerable regularity 

 when the data are averaged over several months or years. Values are based on the 10 least- 

 disturbed days of each month of the interval 1918-1928, using photographic registrations obtained 

 at three of the magnetic observatories listed in Table 510. A plus sign signifies that east declina- 

 tion is greater, or west declination less, than the mean for the day. 



Expressed in minutes. 



TABLE 504.— HORIZONTAL MAGNETIC INTENSITY, UNITED STATES 



This table gives for the epoch January 1, 1950, the smoothed horizontal intensity, H, expressed 

 in cgs units, corresponding to the longitudes west of Greenwich in the heading and the north 

 latitudes in the first column. The remarks about smoothing, in Table 502, apply to this table as 

 well. 



SMITHSONIAN PHYSICAL TABLES 



