ON THE FACTS AND THEORY OF EARTHQUAKE PHENOMENA. 37 
lations upon or within our planet, of its electrical, or magnetic, or thermic 
currents, or the conversion of these into each other reciprocally, and not to 
the direct action of the variable attractive forces of our primary and our 
satellite. To some such conversions of force into heat, developed at local 
foci, it would appear much more probable that all volcanic phenomena are 
due, than to a universal ocean of incandescent and molten lava beneath our 
feet, with a thin crust of solid matter covering it, the present or historical 
existence of which is not only not proven, but for which no argument of 
weighty probability has been, as I conceive, advanced. 
In the present state of our knowledge of the obscure relations between 
the internal mass and actions of our planet with the cosmical forces that 
act upon it both within our own atmosphere and from the abysses of 
space beyond, and in our comparative ignorance even of the terrestrial 
phenomena themselves, no speculation, however hazardous or hardy, that 
is based upon a natural hypothesis, need be regretted: such views in the 
beginning of every separate road of inductive science are eminently sug- 
gestive, and, although in themselves false, may point towards truth. It is only 
in this aspect that a memoir by Dr. C. F. Winslow, M.D., ‘On the Causes 
of Tides, Earthquakes, Rising of Continents, and Variations of Magnetic 
Force,’ requires notice. The communication appears to have been made to 
the Academy of Sciences of San Francisco, California, by the author, in 1854 
or 1855. Ihave met with it only through a printed copy, for which I believe 
I am indebted to the author. 
That our satellite does actually influence the magnet directly, has been 
discovered by Herr Kreil, of the Vienna Royal Observatory (see ‘ Phil. 
Trans.,’ 1857, and ‘ Proc. Roy. Soc.,’ vol. vii. pp.67-75). General Sabine, 
in the introduction to vol. iii. of ‘ Magnetic and Meteoric Observations made 
at Toronto,’ p. 9, states—‘“ The decennial solar period of ten or eleven years, 
in connexion with the solar spots, proved to connect itself with the magnet- 
ism of the earth, but xo¢ with other cosmical phenomena” (see ‘ Phil. Trans. 
1852,’ Art. VIII.); that is to say, I presume, not with such cosmical phe- 
nomena as have had their laws already ascertained. Again (p. xi.), the 
author adds—“ The solar diurnal variation appears to be wholly irrecon- 
cilable with the hypothesis which attributes the magnetic variation to 
thermic causation.” 
We find, then, that both sun and moon influence, with other and more 
occult forces than those that address sense and eye, our planet, and that these 
all incessantly modify the conditions and relations (mutual and to things on 
the surface) of every grain of matter in the inmost recesses of its nucleus. 
While every cosmical force is thus, as soon as its laws are discovered, found 
to be correlated to every other, all mutually convertible, and capable of 
disappearing and reappearing “ by measure, number, and weight,” as mere 
brute power or mechanical force, it is not too much, at least, to affirm 
the advancing probability, that a distinctly (though irregularly) periodic 
phenomenon, such as earthquakes, will be found intimately related to them, 
possibly with no very long or intricate intermediate chain of causation. 
As regards the periodicity, &c., of those solar spots which admit of con- 
sideration in relation to the two paroxysmal maxima and two minima in each 
century (noticed hereafter), Humboldt may be referred to (‘ Cosmos, ’ vol. 
iii. p. 291). Schwabe of Dessau, whose works the illustrious author quotes, 
observed the solar spots from 1826, and, during the whole period, found three 
maxima (average number 300,) and two minima (average number 33,) the 
period being about ten years, or the tenth part of a century. Wolf of Berne 
(‘Comptes Rendus,’ vol. xxx.) considers the period of the minima as de- 
