TRANSACTIONS OF SECTION A. 421 
TABLE SHOWING THE ANNUAL AND SEMIANNUAL VARIATIONS OF THE MAGNETIO 
ELEMENTS AT SEVERAL STATIONS. 
Effect on Declination' | Effect on Horizontal Force Effect on Dip 
At June At June, 
Name of Station At Equin- | Solstice | At Equin-|At June Solstice} At Equinoxes Solstice 
oxes com- | compared | oxes com- compared compared compared 
pared with with |pared with] with December with with 
Solstices | December} Solstices Solstice Solstices December 
Solstice Solstice 
Makerstoun or Kew. | Increase Decrease | Decrease | Inappreciable | Increase Decrease 
Toronto. ‘ . | Increase Decrease | Decrease |} Increase Inappreciable | Decrease 
Cape of Good Hope . | Increase Decrease | Decrease | Increase 
Hobarton . . . | Decrease Decrease | Decrease | Decrease Decrease Decrease 
Trevandrum . . | Decrease Increase 
Bombay . . . | Undecided | Increase 
St. Helena. : . | Undecided | Decrease 
* Increase denotes a push to the west. Decrease denotes a push to the east. 
From this table it will be seen that at all stations where observations have been 
made the horizontal force is, as we have stated above, greater at the solstices than 
at the equinoxes. Also we may imagine that the changes of declination and dip 
which the table exhibits as occurring at the solstices are the very changes which 
would be wrought in these elements by an increase in the magnetic power of the 
earth. For we see very well that an increase of horizontal force at the various 
stations is what might naturally be associated with an increase in the earth’s 
magnetic power. We cannot, however (inasmuch as the earth has the appearance 
of possessing two magnetic systems), see with equal facility what changes would 
be produced in the declination or dip by an increase in power of one or other of 
these systems ; but we may well imagine that such changes of these elements as 
are found to accompany an increase of horizontal force are those that denote an 
increase of power in one or other of these systems. Now it will be seen by an 
inspection of the table that the effect at the Juneas compared with that at the 
December solstice is in all cases but one, of an exactly opposite nature to the effect 
at the equinoxes as compared with the solstices; that is to say, the earth is more 
powerfully affected at June than at December, the only well-established exception 
being Hobarton, in the far south. This means that the polar influence of the sun 
on the north magnetic pole is stronger than its polar influence on the south magnetic 
pole. Now, if we imagine (and there are grounds for this supposition) that the 
action of the sun is in close alliance with the convection system of the earth’s 
atmosphere, we can readily imagine that its influence in the northern hemisphere, 
where there is much land, may exceed that in the southern hemisphere, where 
there is much water. Again, we must bear in mind (so vast is the earth) that a 
stimulus applied to its particles most susceptible of magnetisation may not be 
instantaneously propagated throughout its mass, but that time may enter in as an 
element of the question, in which case, inasmuch as the action of the sun in the 
June solstice is in the northern hemisphere, a station in the far south, like Hobarton, 
may not fully partake of the effects of this action. Allusion has been made to the 
possibility of the earth’s possessing two magnetic systems, a permanent and an 
induction one; at any rate there are two foci of force in each hemisphere, the 
stronger of which in the northern hemisphere is above America, and the weaker 
above Siberia. There is evidence too that the Siberian focus is most subject to 
external influence, and that certain disturbances of declination change their direction 
on different sides of this focus. Let us, therefore, assume that it is this system 
which exhibits the annual and semiannual changes. In this case we might 
expect that the influence on declination at Toronto and Kew, which are on one 
side of the Siberian focus, will be opposite to that at Trevandrum and Bombay, 
which are on the other side. We find from the table that this is the case, and that 
