72 



Franz Schmidt & Haensch, Berlin S. 



III. Spectrum Apparatus for Astronomical Purposes. 



a) Zoellner's Astro -Spectro graph with 2 cylindrical lenses. 

 Dispersion between D and Or : 3. 



b) H. C. Vogel's rectilinear path Astro - Spectrograph. 

 (Fig. 6 a und 6b.) 



Fig. 6 a. 



Fig. 8. 



c) H. C. Vogel's Deflected path Astro-Spectrograph. 2 prisms 

 with scale. (Fig. 7.) 



d) Spectro -Photometer own construction, according to sug- 

 gestions of H. C. Vogel. 



e) H. W. Vogel's Small Spectrograph. (Fig. 8.) 



