372 C. A. Young on a new method 
by a link with the arm which carried the eye-telescope, that 
whenever the latter was moved by its tangent-screw along the 
spectrum the prism box would turn through an angle just half 
as great. Thus the prisms were kept in the position of best 
definition for whatever lines were in the middle of the field of 
view, the extent of which was sufficient to embrace D and E 
together. 
The telescope and spectroscope proper were firmly secured to 
a wooden framework, and this was mounted equatorially, with 
slow motion screws in both right ascension and declination. Fig. 
1 gives an idea of the appearance of the whole. 
lucida prism, and 
inct, 
eclipse the follow- 
17°5 K. (near 
- 
" 
occas) 
* Possibly this may be the ‘fainter red flash’ already described by Mr- Looky" 
to which Lieut. Herschel alludes in a letter to Mr. Huggins published in the Sep 
number of the Chemical News, page 152, American edition. I have not yet seen 
Mr. Lockyer’s notice 
* 
