76 W. A. Norton on Molecular Physics. 
reached its maximum about the year 1855; and that this is near 
the maximum epoch of the secular period of the sun’s spots. © 
In Europe the tendency of the same general cause isto make the 
secular rate the least at the same epoch. In this way, probably, 
it has happened that the increasing secular rate of the easterly 
movement there has become nearly constant.’ 
Observation has furnished the means of testing the explana 
= we have given of the progressive change of pr os 
Dr. Loyd, in his AWctiseton: of the Dublin Observations (between 
1840 and 1843), has established that the needle at Dublin has, 
r 
equinox. ‘The discussions of the observations at Philadelphia, 
and Toronto, have revealed a similar law at those stations, though 
the direction of the annual progression is reversed. No Ww, 
Dublin the new currents developed at all seasons tend to give 
7 From our present Mien portt we ney obtain a Sg Moaed of the origin of the. 
diverse luminous ie of the Aurora Borealis, as well of the attendant 
magnetic ph eran na. We may pereie that the Ais ora is a combined magn 
electric and electro-magnetic phenome —that the auroral Tight results from 
electric prea along the lines of mainte polarization that traverse the masses 
f solar matter, while passing over from the preceding to the fohewitig side of the 
2] 
a 
the preceding side he photosphere ; but in part also to te direct disturbance of 
the electric equim, along the lines of polarization, by these currents, or by the 
ity in the photosphere. e. We here allude, le, especially, to » the more con- 
ceding discussion, - hie it may be advisable to state here, se briefly. a 
- 1. The sun must have become magnetized after the sa’ se eaie as the earth, by = 
reason of its rotation, and of its motion of rotation eoubcaud o h its 
motion through space. As in the case of the earth, there must i eer de- = 
ieearccsanat new currents, tending to exalt its magnetic — i oe currents 
SHOUrG COnCEeNnSe 
the lines of polarization, sere so develop both light and honk: "Tie s 
are probably due to an inverse effect (that is, demagnetizing and dispersi! 
| ; currents di: in th tosphere 
ould a ‘ 
bable that a large fraction of the heat by which the temperature 
walt Pt sun is maintained is the result of th itn sw recurrence of the pro 
