THE ECLIPSE EXPEDITIONS. 
47 
distance of 900,000 miles, or more than 2,000,000 miles from 
the imagined limits of this zodiacal matter, the shadow would 
end in a point. Nor would the penumbra extend far enough to 
hide any but a relatively small portion of the supposed matter. 
It is hardly necessary to point out that no such phenomenon 
has ever been witnessed either in the winter months or at any 
other season. So that, independently of a host of other objec- 
tions, this one — rightly understood — disposes of Oudemann’s 
theory, and of all others which require that matter admitting 
of being rendered visible to us by the sun’s light exists at the 
moon’s distance. 
Yet these radial beams remain to be explained, for I think 
few will be disposed to assert that they are due to mere optical 
illusion.* 
I believe that the chief interest of the eclipse observations 
is not unlikely to be associated with the interpretation of the 
coronal radiations. For, as it seems to me, the difficulty of in- 
terpreting them is altogether greater than that of explaining 
the corona itself. As respects this last, indeed, it seems to me 
improbable that the evidence we have can be made much fuller 
or more convincing than it is at present. But as respects the 
beams we have much to learn before it would be safe to hazard 
an opinion. Nor is it by any means unlikely that we may find 
in these beams a problem as difficult of solution as that pre- 
sented by the phenomena of comets. 
It will be well to consider some of the accounts which have 
been given of the coronal beams. More particularly it will be 
interesting to inquire whether we have satisfactory evidence as 
to their fixity during the whole continuance of totality. For 
though their appearing to change in position would afford us 
very satisfactory evidence as to their nature, their immobility, 
if it could be established, would have great significance. 
It is worthy of notice, at the outset, that accounts refer- 
ring to apparent motion are less likely to be trustworthy than 
those which distinctly state that the beams remain fixed in 
position. For, in the first place, an inexperienced observer 
might very well be misled into the supposition that a radiated 
glory of light had a certain degree of motion ; and in the 
* Oudemann accepts somewhat confidently Dr. Gould’s statement that 
the coronal beams changed in position during the American eclipse. Dr. 
Curtis remarks however, and the study of the various narratives fully con- 
firms the assertion, that all the other observers describe the rays as fixed in 
position. I do not know that their apparent movement, if confirmed, could 
be regarded as demonstrating anything as to their nature ; but in this, as in 
other cases, all the best authenticated accounts speak of them as remaining 
unchanged. 
