190 E. H. BOOTH. 
light, allows detail to be seen in both the densest and 
clearest portions at the same time. 
If a print be taken from the negative, however, the 
picture is viewed by reflected light, the actual light pene- 
tration being slight, and consequently the range of contrasts 
must be slight also. 
Whilst, therefore the negatives may, and do, show the 
prominences, the fine polar streamers, and the main coronal 
detail all at the same time, it is not possible to reproduce 
these all sharply on the one print. A transparency is much 
better, as already explained; but to get the maximum value 
from the negative it is imperative that a series of prints 
should be made. The effect is the same as though many 
plates of widely differing exposures had been taken. 
The plates of the Sydney University Eclipse Expedition 
have been treated in this manner, the best plates being 
taken as the basis of a series of prints. 
As aconcrete example, the plates of greatest interest in 
the case of the 16 foot coronagraph are the first (just after 
second contact), the sixth (just prior to third contact), and 
one intermediate plate (the third was chosen). Prints 
were taken from these on Velox Glossy Regular paper, 
the exposures being on the “double up” principle. The 
developer used was the laboratory standard Metol-Quinol 
1:15, plus two drops of 10% solution of potassium bromide 
per ounce of mixture. The prints were fixed in hypo (1:5), 
rinsed, hardened in an alum bath, and ferrotyped after 
washing. The actual times of exposure of course depended 
on the negative, but the relative values will be seen from 
one case, particulars of which are set out in Table I.. The 
“dull light” referred to was an 8 c.p. carbon filament, the 
‘bright light’’ a 300 c.p. half watt lamp. ‘‘Close’’ was 9 
inches, ‘*‘ far removed’’ was 3 feet. | : 

