( 605 ) 
The opening and closing of the shutter of the prismatic camera 
might have caused a vibration, probably chiefly in an horizontal 
plane; the fact however that the doubling is not constant in one 
and the same exposure, and on the other hand shows itself in the 
same manner both in the long and in the short exposures, makes 
also this explanation entirely unacceptable. 
No more can a considerable error of focussing be admitted, since 
on plate 6 lines are shown parallel to the direction of dispersion 
— Bailey’s beads drawn out into lines by the prisms — which 
have a breadth of only 0.06 mm. 
Finally, as far as we can see, every instrumental explanation 
must fail through the fact that the distance of the components ofa 
double crescent is very different for different crescents, while also the 
direction of the doubling and the relative intensity of the compon- 
ents is variable. Moreover the corona-ring 43987 is, on plate 
3, sharply outlined on the concave side. (On plate 2 this ring is 
too faint to state the same fact with certainty). On comparing this 
outline with that of the neighbouring crescents of calcium (H and K), 
which are very distinctly double on the same plate, there can hardly 
remain any doubt as to the reality of the doubling of the chromo- 
sphere-lines. The light of the corona-rings on the other hand appears 
to be more purely monochromatic. | 
A reproduction of part of the first exposure on plate 6 is appended 
to this preliminary report (Plate IJ, enlargement about 4 times) in 
order to enable the reader to form an approximate idea of the 
character of the double lines. The original negatives of course show 
many more details, such as Fraunhofer lines, etc., which would also 
be visible on a darker copy. 7’his copy has however purposely been 
kept fainter, in order to bring out clearly the almost linear flash 
spectrum formed by the lowest of , Bailey’s beads”. The wave-lengths 
given in the figure are relative to this spectrum. 
Enlargements of the other exposures will be published afterwards. 
The doubling which was observed by us is also shown on previous 
flash-spectrograms ; it appears however not to have drawn the attent- 
ion of observers. See e. g. the crescents of A 4584, 4572, 4564, 
4554, 4550, 4534, 4501, 4472, 4341 etc. in the spectrograms which 
were obtained by FowLeR with the „6 inch Prismatic Camera” during 
the eclipse of Jan. 22 1898. 
When once the attention has been directed to this point, on these 
photographs too nearly all the crescents appear double, though less 
distinctly. 
40 
Proceedings Royal Acad. Amsterdam. Vol. IV. 
