68 J. C.F. Zillner on a new Spectroscope. 
apparatus of the spectroscope. This can be easily accomplished 
using a collimator with a relatively short focus to that of 
the object-glass of the refractor. Suppose, for example, we have ¢ 
a ten times greater contrast with the spectrum back-ground. 
Tn order now to obtain again the amplification of the protuber- 
ance in the field of view, which was lost by the diminution of the 
sun's image, the focus of the collimator need only be made ten > 
times shorter than that of the spectroscope. To continue with 
the example proposed, a ten times better effect would be obtained, 
giving the same optical amplification of the protuberance with the 
same prism systems, if there is chosen in place of the ten feet 
refractor a telescope of only one foot focus, and for the focal 
distance of the collimator about two inches, and that of the 
. 
og eee > —_ 
= r at 
OLU DeLa 
rvation in the future of all the protube- 
the sun’s limb at the same tim 
