No. 54 096. 



Spectrum Apparatus and Accessories. 



507 



54092. 1:8. 



54 095. 1 : 6. 



54.089. Interference Plate after Lummer-Gehrcke, Figure, in mount, for using ordinary 

 spectroscopes as Interference Spectroscopes, for demonstrating the Zeeman effect, etc. ; 

 also specially adapted for Spectrometer No. 54,087, for obtaining high resolving power 



54.090. Echelon Grating after Michelson, Figure, for the same purpose 



s. d. 



12. 10. 

 12. 10. 



11. 5.0 

 23. 0.0 



54.091. Interference Plate after Fabry and Perot, standard of approximately 10 mm air 

 distance, for measuring wave lengths by utilising Haidinger's Interference Rings; can 

 be used with Spectrometer No. 54,087, with quartz hollow cylinder of low temperature 

 coefficient between the boundary plates 



54.092. Spectrum Apparatus with a Rutherford Prism, Figure 



The observing telescope and gap-tube have an aperture of 30 mm and focal length of 312 mm. 

 The telescope is a power 10 instrument; diameter of plate 180 mm; telescope focussed by micrometer 

 screw; arc divided in '/u with vernier, in one piece with the alidade of the telescope, permitting a 

 reading of 12", by which the position of the lines in the spectrum is determined. Gap with micro- 

 meter screw and comparison prism. The dispersion from A H 2 is 14. The two D-lines are at an 

 angle of 1' 36" to each other; the fine nickel line should be plainly visible between these when the 

 instrument is correctly focussed. 



54.093. --the same apparatus, with arrangement for convenient reading of the 



scale parts 26. 0. 



A reading tolescope is fixed above the observing telescope and parallel to the same. The former 

 telescope has a right-angled prism at the end and brings to the vision of the observer by reflection 

 the graduation of the divided arc and of the vernier. 



54.094. Spectrum Apparatus, as No. 54,092, but smaller pattern; observing telescope with 

 aperture of 27 mm and focal length of 230 mm, power 8; a gap-tube of the same dimen- 

 sions; with brass plate on which both tubes are mounted, of 155 mm diameter; graduated 



arc divided in 1 / 6 , vernier giving 30" 18. 0. 



54.095. Spectrum Apparatus, F i g u r e, same size as No. 54,092, but instead of having a 

 Eutherford Prism is fitted with a 60 prism constmcted of extra heavy flint glass and 

 with a dispersion of 7. The position of the lines in the spectrum is in this case de- 

 termined by a telescope with photographic scale instead of by divided circle. The 

 observing tube can be adjusted by micrometer screw. Gap with micrometer screw and 

 comparison prism 14. 0. 



54.096. Spectrum Apparatus with observing telescope and gap-tube of 27 mm aperture and 

 230 mm focal length, with the scale telescope mounted on a brass plate 135 mm in 

 diameter; observing tube without rack or micrometer screw; gap with micrometer 



screw and comparison prism 7. 10. 



This apparatus is very efficient in spite of its low price; externally it resembles very closely 

 Fig. 54,095. 



Cl. 5595, 5372, 

 6055, 1384. 



