and Directive Force of the Magnetic Needle. 191 
rents flow in all digections, diametrically opposite to the point 
directly under the sun. If the electric excitement of the upper 
atmosphere by the sun be indeed a consequence of the propaga- 
tion of avibratory motion (or impulse) by ethereal waves, then I 
conceive that the concentration of the separate currents (individual 
pulses) at the point diametrically opposite the sun would give 
rise to a certain increase of excitement, and to currents of a cer- 
tain intensity flowing in every direction outward from this point 
along the surface of the atmosphere. The resistance experienced 
by the individual currents flowing from the point under the sun, 
together with the diminution from the very law of propagation, 
should cause the intensity of the electric excitement at this second 
point to be less than at the first ; and accordingly the needle should 
be less effected at night by the passage of this point along the upper 
atmosphere than during the day by the passage of the point di- 
rectly underneath the sun. If the entire mass of the earth should 
be partially transparent to the wave or force propagated from the 
sun, then a certain degree of excitement would be produced, at 
the point diametrically opposite to the sun, by the sun’s direct 
action. 
I infer from certain theoretical considerations, on physical 
grounds, that the radial current proceeding from the two points 
of maximum electric excitement should be attended with trans- 
Verse impulses (or circular currents) of a feebler intensity. Such 
ra 
I have hitherto regarded the point of the photosphere directly 
under the sun, as the only point electrically excite by the sun’s 
action, and from which the currents flow; but on theoretical 
8tounds other points upon which the solar emanations fall should 
