PROCEEDINGS OF THE CANADIAN INSTITUTE. 12& 



Auroral Phenomena, Sun-Spots and Magnetism. By Arthur Harvey. 



{Read 2Sth IVovember, !')(>J.) 



Mr. Andrew Elvins having stated in a recent paper that magnetic storms 

 were more frequent at the equinoxes than at other seasons, I have prepared a 

 diagram to show the times at which such storms have occurred since 1881. Were 

 it not for the encumbrance to distinctness I would have gone back tifty instead of 

 twenty years. There is no greater frequency at the equinox. The points mark 

 the depressions in the curve of magnetic Horizontal Force at Toronto, and indicate 

 not only the dates of magnetic storms but their relative intensity. 



Mr. Elvins produced a statement from the Washington Weather Review 

 that Tromholt's auroral catalogue showed some excess of aurorte at the equinoxes. 

 I was aware and had myself stated when jMr. Elvins read his paper that there had 

 been a slight excess of magnetic tremors noticed about the equinoxes by the United 

 States observers at Los Angeles — and to see if this were really reflected by a sliglit 

 excess of aurorte, I made a study of the interesting catalogue of Norwegian aurone, 

 the life-work of the late Dr. Sopbus Tromholt, of Christiania, edited by Prof. I. 

 F. Schroter, of the Observatory there, at the joint cost of the Scientific Association 

 of that city and the Fridtjof Nansen Fund. I found a very slight excess of aurorse 

 observed in March and September, but it was accounted for by quite other reasons 

 than Mr. Elvins supposed, namely, by climatic obstacles to observation in the most 

 northerly regions of the Scandinavian peninsula, where for nearly half the year 

 people do as little outside observation as possible, and during most of the other 

 half, twilight or actual sunlight renders auror;e invisible. It is plain that about 

 the equinoxes the conditions for observation are more favourable, and the wonder 

 is, not that there should be a trifling excess observed, but that the excess should 

 be so very small. 



There were, however, other things of interest to be gathered from Tromholt, 

 some of which are to be alluded to in the present paper, which is intended to be a 

 new historical proof that aurorte are especially prevalent during years of solar 

 activity, and that their numbers and brightness correspond accurately therewith : 

 also to illustrate the changed position of observers of such meteoric phenomena 

 in that superstitions regarding them are fading ; and lastly to touch on some in- 

 stances of the wide extension of remarkable auroral displaj^s. 



The earliest allusion to Scandinavian aurora' is that in Tacitus (" Germania," 

 chapter xlv.) : "On the farther side of Swedes-land is another sea, dark and almost 

 motionless, which is thought to girdle and enclose the terrestrial orb, because there 

 the last light of the setting sun endures until its rising again, so brightly that it 

 dims the stars. Moreover it is credibly reported that sounds are heard there and 

 the shapes of gods seen, with radiance around their heads." Pliny puts us on the 

 track of earlier aurorre when he says ("Natural History," Book I., chapter xxvii.): 

 " There is a flame of a bloody appearance, and nothing is more dreaded by mortals, 

 which falls down upon the earth, such as that seen . . . when King Philip was 

 disturbing Greece." Also that " a bright light has been seen issuing from the 

 heavens in the night time, so that there has been a sort of daylight at night, as 

 was the case in the consulship of L. Valerius and Cn. Papirius." The date of L. 

 Valerius was 462 B.C., when the Romans were having a troublesome war with the 

 iEqui, and, says Livy, "the heavens were seen to be on fire with a very great 

 flame," so a three days' penitential ceremony was ordered, during which crowds 

 of men and w^omen thronged the temples, begging the angry gods to stay their 

 hand. Three years later the sky was seen on fire again, there was an earthquake, 

 and a bull was heard to speak. The King Philip trouble was about 200 B.C. 

 (Livy xxi., cap. 12) when again the heavens were aflame, and the priesthood saw 

 their opportunity for interpreting the natural phenomenon in their peculiar way, 



