84 P, E. Chase on influence of Gravity on Magnetic Declination. 
depending on the sun’s declination. The diurnal range 1s 
greater when the sun has north declination, and smaller when 
south declination; the phenomenon passing from one state to 
the other about the time of the equinoxes.” [Part II, p. 10. See 
also Toronto Obs., 2, xvii; St. Helena Obs., 2, exviii). 
II. “At the hour of 6 or 7 in the morning, the annual varia- 
tion is a maximum, disappearing at a quarter before 10 A. a, 
and reaching a second (secondary) maximum value at 1 P, M. 
It almost disappears soon after 5 P. M., and a third still smaller 
maximum is reached after 9 P.M. Half an hour before mid- 
night, the annual variation again disappears. At (and before 
the converse is the case.” [Ibid., p.12. Compare St. Helena 
, 2, cxvili; Toronto Obs., I, xiv, and 2, xvi. 
III. “According to the same authority,” [Gen. Sabine], “the 
annual variation is the same in both hemispheres, the north end 
the law of the annual variation is the same, and that of the 
diurnal variation the opposite in passing from the northern to 
the southern magnetic hemisphere.”  [Ibid., p- 18. Comp. St. 
vi 
IV. “The regular progression of the monthly values is a 
feature of the annual variation deserving particular notice. 
