196 W. A. Norton on the Variations of the Declination 
ation.” What is remarkable, we are also assured that an annual 
variation of the declination at the same hour of 7 to 8 a.m, “ 
most precisely similar in character and amount,” obtains at Ho- 
barton, which is nearly diametrically opposite to Toronto, and 
also at the two intertropical stations of St. Helena and the Ca 
of Good Hope, and is probably therefore a general phenomenon. 
It will be seen upon a little examination that it is a simple con- 
sequence of the shifting of the position of the radial current pro- 
ceeding from the point underneath the sun, which may be taken 
as the representative of all the radial currents in action at the 
hour in question. To show this let us first suppose the station 
to be on the equator. At the hour of 7 to 8 o’clock a.m. the 
point of maximum excitement will be on the 6 o’clock hour cir- 
cle, as it lags an hour or two behind the sun. (See p. 192.) Now 
let EQ, Fig. 5, be the equator, as traced on the photosphere, P 
> 
Ls] 
the zenith of the station of the needle, N the position of the 
point of highest intensity at the time of the northern solstice, 00 
the 6 o’clock hour ciycle, and S the same point at the time of the 
southern solstice. NPE=EPS=234°. The meridional com- 
ponent of the current along NP will be directed toward the 
south, that of the current SP toward the north. The former 
will displace the north end of the needle toward the east, the 
latter toward the west by an equal amount. (A transverse eur- 
Tent, in the present instance, could have no effect, since It 
would be equally inclined to the meridian at the two solstices, 
and solicit the needle with the same force toward the east.) 
