That figure, it will be recalled, shows what happens to precipitation when solar activity is increasing.
The cycle of sun-spot change is attended by marked changes in many forms of solar activity.
In this connection, however, it must be remembered that solar activity may arise in various ways, as will appear more fully later.
There is clearly a connection between the solar activity as shown by the spots and the agitation of the magnetic needles.
As to causes, variations in solar activity are naturally receiving attention, and the results thus far are promising.
An unaccountable suspension of solar activity is, in fact, indicated.
It is given here because ultimately the question of changes in solar activity during geological times must be faced.
The degree of solar activity would have much to do with the final extent of the ice sheets.
At the times of both of these eclipses the solar activity was decreasing.
Two rather slender bits of evidence point to cycles of solar activity lasting hundreds of years.