3i8 The American Geologist. November, 1904. 
In view of the fact that ohservations have recorded a cor- 
responding and simultaneous variation in the solar activity, 
it is, indeed, remarkable to notice how the magnetic waves 
from the sun, are registered by the moon as they approach 
the earth and manifest themselves in atmospheric agitations. 
§11. THE CAUSE OF THE LARGE INCLINATION OF THE ORBITS 
OF CERTAIN PLANETS TO THE ECLIPTIC. 
Observations show, that the eruptions and protuberances 
df the sun are greatest and of more frequent occurrence in the 
sun's equatorial region, and that the activity of the light pow- 
er, as a rule, is greatest there. From this it follows, that the 
light-stuff is relatively denser and more powerful in the eclip- 
tic than towards higher latitudes on either side of it. The 
swiftest planets, which are nearest to the sun, consequently 
meet the greatest resistance in the ecliptic. Now since this 
resistance decreases in proportion to the rarification of the 
light-stuff north and south from the ecliptic, it follows natur- 
ally that these planets intersect the ecliptic and incline to it 
in the same manner as the moon. 
For the reason, then, that the light-force is stronger in 
the ecliptic, and most active nearest the sun, the orbit of, the 
planet which is nearest to the Sun and has the greatest ve- 
locity, also' has the greatest inclination to the ecliptic. 
Leverier, thus, found an inclination of 12° for A'ulcan, a 
small planet between M'ercury and the Sun. INIercury has 
an inclination of 7° and Venus 3J^° from the ecliptic. 
The decrease in the inclination of the orbits of these plan- 
ets in proportion to the increase in the distance from the 
Sun, is thus a result of two causes, principally, namely, the 
diminution of the light-force and the decrease in the planet's 
velocity simultaneously with the increase of the distance. This 
decrease in the inclination as the distance increases, depends, 
further, upon the size of the 'planet, since a smaller planet 
meets a greater resistance proportionately to its mass than a 
larger one. Mercury would thus have had a greater inclina- 
tion in the orbit of Venus than Venus itself has ; and Venus 
would, therefore, have had a less inclined orbit at ^Mercury's 
distance from the Sun, than Mercury itself has. 
This circumstance, that the resistance oi the light-force is 
greater proportionally in relation to the power and mass of 
