PROCEEDINGS OF THE CANADIAN INSTITUTE. 



37 



or has it passed beneath the great spot and been eclipsed by it, or in some way 

 mingled with it? 



I hope photographs which have donbtless been taken will answer these 

 questions. 



On the 14th it was bad seeing but I made a rough sketch ; the large spot was 

 near the limb, one part of the penumbra was on it and only one spot could be seen 

 following it ; it probably passed over the limb on the 16th which was just fourteen 

 days crossing the disc, and it came on on the 2nd. 



The motion of the earth in its orbit adds about two days to the time which 

 the sun's rotation alone would require to enable us to see a spot which is on either 

 limb of the sun until it returns there again, about twenty-seven days together, and 

 as this spot was on the east limb on the 2nd, it should be there again on the 29th. 

 It appeared at the proper time but greatly decreased in size, and quite shorn of 

 the fine train of spots seen when it was last visible. 



Two spots, however, preceded it ; the first must have been on the limb on the 

 27th. I saw it on the 28th and stated in a letter that the large .spot had retui-ned ; 

 I was mistaken in this, it was too early ; the great spot was on the limb on the 

 29th and my first sketches were made on the 30th. 



But the smaller spots which preceded it may have special interest. We 

 noticed the fact that the spots in the train following the large one when it was 

 last seen approached the large spot and seemed to coalesce with or pass beneath or 

 above it, and it is possible that the spots which followed it, may precede it now ; 

 if the westward motion continued during the fourteen days when they Avere 

 invisible to us they Avould have passed to where we see them noAV. 



On October 1st the great spot Avas Avell in on the disc ; it contained thx'ee 

 pretty round black umbras and the penumbra Avas nearly circular, and tAvo spots 

 preceded it, the foremost one the largest. 



From this time the size and activity of the spot gradually diminished, though 

 occasionally very bright bridges, and bright points were seen. On the Gth the 

 three umbras diA'ided, and on the 8th four Avere plainly Aisible, the spaces betAveen 

 them being intensely Avhite. I saAV it last on October 10th, near the western limb ; 

 it Avas cloudy on the 11th and on the 12th it had disappeared. 



I should note that the small spot preceding became more Avidely separated as 

 time passed on. 



I Avish to state here as I have often stated before, that I see no evidence in 

 this spot of spots being deep hollows in the photosphere ; the di-ifting of the groups 

 in the train in September toAvard the large spot, and the drifting of the spot 

 preceding it in October, from the large spot render it far more probable that dark 

 matter floating and drifting in the sun's atmosphere cuts off the light of the 

 photosphere beloAv, and is seen by us as a spot. 



It is more than tAventy years ago since I called the attention of this Institute 

 to the influence exerted by sun-spots on the earth and its atmosphere. Prof. 

 Loomis of Yale Avas Avorking at that time on the subject, and had shoAvn that 

 magnetic disti(rbances and our auroras are more numerous Avhen sun-spots are 

 numerous than at other times ; but whether they were directly influenced by solar 

 disturbances, or are caused by cosmical conditions Avhich attect both earth and 

 sun Avas by no means certain. In the case of the present spot there has been a 

 very marked magnetic disturbance just as the spot passed the central solar 

 meridian, and at the same time, September 9th, brilliant auroras Avere seen in 

 Europe, and also very generally through the Dominion of Canada. 



Dr. Vedder and Mr. Shearman have noticed auroras and magnetic storms. Avheu 

 spots Avere near the eastern limb of the sun ; European observers have noted such 

 displays Avhen the spots Avere on the sun's central meridian. 



In the case of this spot, in Canada auroras Avere reported from thirteen 

 stations on the 2nd of September, and from tAventy-one on the 9th. and again on 

 the 28th and 29th, when the spot had made one complete revolution and was 

 again on the east limb, auroras Avere reported from many stations. So in this 

 instance Ave have a plus of auroras Avhen the spot Avas on the eastern limb and 

 also Avhen near the centre, Avhilst very few are reported at other dates. In this 

 case both the American and European observers may be right as to the facts : and 

 our theories of the cause of the coincidence Avill have to inclmh' both. 



