( 604 ) 
On plate 1 only a small number (9) of chromosphere-crescents 
are visible; the second contact is badly shown owing to the clouds. 
On two of the four corona plates (Nrs. 2 and 3) the ring 
43987 is but faintly visible, these exposures naturally being 
much impaired by the disturbing influence of the clouds. 
The third contact appears to have occurred at a relatively clear 
moment. Plate 6 shows a large number (150) of chromosphere- 
crescents between 43880 and 45000, in different phases of the 
flash phenomenon. Especially the first exposure on this plate 
(2s after third contact) is very rich in details. The spectrum appears 
to be well focussed over its entire length. 
Prof. W. H. Junius has already pointed out!) the very remark- 
able fact that every one of these chromosphere-crescents is double ; 
the distance of a pair varies from 0.7 to 1.6 #. m. 
Though we have given much thought to the question, we are 
unable to ascribe this doubling to instrumental causes. The distance 
of the components of a pair is in the mean 0.13 mm., 1. e. about 
11" of arc. The doubling, though different for different crescents 
and for different parts of the same crescent, has a very decided 
preference for one direction, inclining 9° (counted from N. through 
E.) to the parallel, or 15° to the horizontal, 22° to the ecliptic 
and 29° to the sun’s equator. 
Though we do not wish to go too much into detail in this preliminary 
report, we may be permitted to mention that the most important 
instrumental causes which offer themselves for explanation of the 
observed doubling, are the following three: 
1st irregularities in the rate of the driving clock of the siderostat, 
2nd a vibration of the prismatic camera or of its parts, and 
3rd defective focussing. 
On closer examination it appears to us to be very improbable 
that any of these causes has been effective. It is true, during the 
last exposures with the 40-feet coronagraph the clock of the sidero- 
stat seems to have performed badly, but «// plates of the prismatic 
camera show the same doubling, as well the exposures of °/, sec., 
as those of 608 and 190s, and both at the first and at the last 
flash. Moreover there is no question of a diffused appearance of the 
images, but of a doubling, in a direction differing from that of the 
parallel. 
1) W. H. Junius, On the origin of double lines in the spectrum of the chromosphere, 
due to anomalous dispersion of the light from the photosphere. Proceedings Royal 
Ac. Amsterdam, Vol. IV, p. 195—208, 
