1889 | VEEDER—ON THE AURORA. 19 
netic needle. Fine auroras also have been seen during the entire absence 
of such spots. These exceptional cases are sufficiently numerous to 
prove that all sun spots, or, according to another view, sun spots in all 
locations upon the earthward side of the sun, are not capable of origi- 
nating auroras. The occurrence of auroras in the absence of sun spots 
shows that there may be something else, increasing and diminishing in 
like ratio, that is concerned in their production. Very little systematic 
observation is required in order to make it plain that the outbreaks of 
glowing vapors known as the faculz have an even more direct relation 
than the spots to the occurrence of the aurora. These vapors have 
been seen to be projected upwards at points on the sun’s limb with 
velocities as extraordinary as two hundred miles per second. The 
dark spots on the other hand are simply depressions resembling whirl- 
pools that form in the vicinity of such outbreaks. Photographs have 
been made showing the notch formed by a dark spot upon the sun’s 
edge. From this it is evident that the eruptive forces find their direct 
expression in the formation of the faculee, sun spots being a minor and 
subordinate result. Indeed disturbed areas have been seen to persist 
through successive revolutions for months together without the forma- 
tion of dark spots, each return of the glowing points of facule being 
attended by auroras and magnetic perturbations. Thus it becomes evi- 
dent in what way auroras may occur in the absence of dark spots, 
although auroras, sun spots and faculz maintain a very similar ratio to 
each other, sun spots being more numerous when the sun is much dis- 
turbed, although not the most direct and positive evidence of solar 
activity. 
This explanation of the occurrence of auroras in the absence of 
dark spots increases the difficulty however at another point. Although 
the sun is often free from spots it is scarcely ever free from groups of 
faculz making the transit across its earthward side. Two such groups 
at an interval upon the sun’s surface of thirteen days from each other 
would be sufficient to insure that one or the other should always be 
directed towards the earth, the one appearing at the eastern limb as the 
other disappears, by solar rotation, at the western limb. Accordingly it 
might be supposed that under such circumstances, auroras ought to 
continue all the time, or if there were but a single disturbed area that 
scme evidence of its power to produce magnetic phenomena ought to 
be apparent more or less, throughout its entire transit, or during thirteen 
days at least at each return. Asa matter of fact, however, auroras are 
comparatively short lived, even in the higher latitudes, and within the 
bounds of the United States are rarely seen at a single station for more 
