PROCEEDINGS OF THE CANADIAN INSTITUTE. 135 



fairly well collected uow, were in an imperfect state from 1878 for several years. 

 It is, however, fairly clear that the Tromholt tables give but slight countenance ta 

 Sir Norman Lockyer's 35-year period between important minima. It appears be- 

 tween 1776 and 1811, and perhaps between 1811 and 1845.5, but the only auroral 

 minimum which could fit in before 1776 was in 1738, which is thirty-eight years 

 before, and the one at this end of the series, following 1845.5, was in 1879, or 

 33.5 years apart. These divergences are too wide to base a law upon. 



The solar prominences are now being sub-classified, T hope. The observations 

 appear to be separating the common form of hydrogen prominence from the metal- 

 lic prominences. While in our "Transactions" I have recorded my inability to 

 detect magnetic effects consequent upon the former, which are by far the most 

 frequent, I do find a connection with the latter. We are upon the eve of important 

 solar discoveries, and another step in advance towards a knowledge of his constitu- 

 tion and the problem why the Geyser-like intermission of the eruptions upon his 

 surface occurs. It will assuredly not be the sun's passage through matter floating 

 in strata in space, which is an old theory Mr. Elvius has not yet chosen to 

 abandon. 



We can see by the Tromholt auroral curve, as well as by the spot curve placed 

 in juxtaposition, whdt a shamefully irregular body the sun is, and how little de- 

 pendence can be placed upon his ill-understood whims. Adverting now especially 

 to spots, not only are the periods uneven, varying on the interval before us from 

 7.3 to 17.1 years between maxima, and from 9 to 13.6 years between minima, but 

 the amounts of spottiness attained during his pulsations of energy vary, too, some 

 maxima being three times as marked as others, that is, the spots cover three times 

 as much solar area. Galileo had no trouble in seeing and drawing sun-spots in 

 1510-13, but his successors were less fortunate, for, as Miss Agnes E. Gierke tells 

 us, a prolonged solar calm set in about 1643, aud only a few solitary spots were 

 seen in 1660, 1671, 1684, 1695 and 1705, which Professor Maunder happily calls 

 "the crests of a sunken spot-curve." As to aurora^, the earliest Norwegian ob- 

 server says : "When I was a child, about 1550, they were for the first time seen 

 in the southern regions of our country, butsiuce 1570 they have been rising so high 

 that they can even be seen in places to the south-east aud south of us, aud 1 think 

 they may now be viewed in other countries, too." It seems, however, rather 

 astonishing to learu that no aui-orfe were seen in England from 1575 to 1706 — a 

 hundred and thirty-one years. From 1790 to 1815 there were very few seen in 

 Norway, and not many for ten years more, after which they again became frequent. 

 The correspondence between the recent solar minimum aud the magnetic and 

 auroral minima has not yet been thoroughly examined, but at Toronto the records 

 show, on the magnetic traces, during the rather prolonged and very marked solar 

 minimum, which reached its nadir in 1901.7, an almost continuous straight line. 

 In Christiania, Milan aud Prague, the least average variation in declination was in 

 1902, another "lag" as compared with the spot minimum, and the same feature 

 may be evidenced when the Toronto records are digested. The aurora" observed 

 here in 1901 and in 1902 were equal, but less than in any year .<iince 1878. In this 

 year, 1903, sun-spot activity is markedly revived, also magnetic variations, earth 

 currents and aurone. 



As to the cause of auroral light, the new theory of corpuscles seems to apply — 

 particles shot off from the sun being constrained to move in .«piral pulses along the 

 lines of magnetic force as they approach the earth's surface. As they move from 

 the upper regions of the air towards the poles they go through air strata so rarefied 

 that luminosity can be easily excited (as when an electric current passes through 

 a nearly exhausted receiver), but as they approach the earth the density of the air 

 forbids their luminescence. So far the theorists, and perhaps we had better for 

 the present suspend judgment. The rapidity of the motion of electricity would 

 scarcely allow the eye to follow it, as it does in the case of the aurora, even at the 

 ascertained height of auroral displays here, say 100 miles. W^e should see some- 

 thing resembling the lighting's flash for swiftness. Possibly the radiations which 

 convey electrical charges from sun to usward move more slowly than those we feel 

 as light, which might account for the peculiar " lag " of magnetic eftects. 



The localization of auroral eflfects is also very strange. The same aurora is 

 seen differently in different regions. This was made curiously evident in examin- 



