34 W. A. Norton on the Variations of the Declination 
(nearly)... (22). From which it appears that both E and R 
are less than as determined by eqs. (20), and that the diminution 0 
, by reason of the residual currents, exceeds that o 
quantity 7+e. 
currents because these currents now proceed from the portion 
the photosphere which is diametrically. opposite to the sun (p. 191 
and are weakened by the currents proceeding from the points u 
derneath the sun; and that of the ecliptic currents because the 
. the southern he 
versed an i 
nocturnal ecliptic currents 
smentation of horizontal force a 
ter midnight ; but in some instances they only suffice to che 
e action of the radial ¢ 
the gradual subsidence of the residual currents consequen 
the sun’s action during the day. (See curves of variatiou 
of horizontal force during the summer months, at Toronto 
Hobarton, in the Hobarton Observations, Vol. I, p. 54.) 
Annual Variations. 
These as observed at Toronto, may be studied in Table | 
diurnal range, the amount of the range being considerably grea 
o March: 
change in the hours of the maxima and midima; especially in| 
hour of the principal minimum, which is at 9 or 10 a.m. fi 
of the horizontal force; the maximum being in June an 
minimum in December. Preparatory to the explanation of th 
Variations let us compare the mean semidiurnal effects of - 
radial and ecliptic currents in the different months of the yé 
For this we have (disregarding the residual currents) the | 
(20) (p. 33), which give the following results : 
Be .ce | Jan. “| Feb. March. | April, May, June. | July.) Aug. |Sept, | Oct.) 2 
eR | i05 | 18 | 295 | 635 | 56 | 585 | 50 |.48 | 48 | 2 | 
E 11085 1 82 | 975 | 785 | 39 | 485 | 36 | 48 | 99 | 72 
