i882.J 
599 
Sunlight . 
experiments, light and heat ; and the chances are greatly in 
favour of such light and heat originating in a huge electric 
discharge. But as it would be difficult fo account in this 
way for all the heat received at the earth’s surface, it is pro- 
bable that the original discharge is comparatively cool, and 
that it becomes heated only when it encounters a resisting 
medium such as the earth’s atmosphere. 
Supposing sunlight to consist of an eleCtric discharge, it 
is probable that on striking the earth’s surface it travels 
over the whole of the illuminated side in a series of curves 
radiating as it were from near the Equator towards the 
North and South Poles, where, when the earth becomes 
fully charged, the discharge makes its escape, and appears 
to us as an Aurora or some other familiar phenomenon. 
The supposed direction in which the terrestrial currents 
travel may be well seen by sprinkling a small quantity of 
fine iron-filings on a piece of cardboard held over a bar- 
magnet. The two points where the lines of force converge 
will represent the north and south magnetic poles, and a 
line drawn equidistant from and at right angles to these 
two points will represent the magnetic equator, and the 
lines diverging from the outside of the poles the return 
current. 
At first sight it would appear that this comparison was 
fallacious, as it is obvious that if the curves joining the two 
converging points were insulated, and an eleCtric current 
passed from the outside towards the centre, or vice versa , the 
effect would be not to form two poles, but only one, situated 
on the equatorial line. But if matters were so arranged that 
the current travelled in different directions, from the equa- 
torial towards the converging points, the effeCt would be 
changed, and we would have two poles, one of which would 
attract and the other repel the north pole of a magnet. 
If these latter speculations be correct we might be able to 
find an explanation of the secular, annual, and diurnal vari- 
ations of the compass, on the assumption that such variations 
were caused by a slight change in the direction of the cur- 
rent, owing to the revolution of the earth, and also to the 
presence of induced currents on the non-illuminated side. 
As the objeCt of this paper is to present the speculations 
contained therein in a general form it will be unnecessary at 
present to go into details, but rather to try to prove shortly 
that the aCtion of motion on attraction results in sunlight; 
and the most direCt proof that can be brought forward will 
be found in the appearance that a comet presents in its 
approach to and departure from the sun. 
