506 



Spectrum Apparatus. 



No. 54 083 



54 083 B. 1:5. 



54086. 1:5. 



Repeating Spectrometer, Figs. A and B, with two telescopes of 2(! nun aperture s. d. 

 and 234 mm focal length, with Gauss Ocular, with concealed circle and arrangement, 

 for carrying out goniometric measurements by Wollaston's method 41. 5.0 



The circle is divided in '/4 on silver and permits of readings by a magnifying glass and two 

 verniers to 2o". Fig. A shows the instrument set up for use as a spectrometer, and Fig. B for use 

 as a goniometer. 



54,084. - - idem, without concealed graduated circle or arrangement to permit of gonio- 

 metric measurements being made by Wollaston's method 33. 0. o 



A Gauss Ocular is given in for goniometric measurements. 



Spectrometer after v. Lang, see Fig. 53,827, p. 482, practical school model for laboratories, 

 with concealed circle and magnifier reading; also adaptable as goniometer, without 

 prism 15. 0. 



54.086. Wave Length Spectrometer with variable Deflection, Figure, especially adapted 



for rapid and accurate measurements 32. 10. o 



The apparatus has a <|iiadrilatcral prism which totally reflects and refracts the light. The stage 

 is arranged to rotate so as to be able to determine the wave lengths of the spectrum-lines observed. The 

 wave lengths are read direct on a spiral drum. 



Focal length of observing telescope and of the gap tuhe 2!).-J"> cm. aperture :il.:> nun. 



54.087. - - i de m, with lengthened arm for the gap-tube in order to be able to place on it 

 a Michelson Echelon Grating (No. 54,090) a Lummer-dehreke Plate (No. 51,0*9) "i 



a Fabry and Perot Air-plate (No. 54,091) 45. 0. d 



54.088. Micrometer Ocular for above, for measuring t lie diameter of the Haidinger Intciiercnec- 

 ring System when using the Fabry and Perot Interference Air-plate No. 51. (MM as an 

 auxiliary to the Echelon grating and the Lummer-Gehroke Parallel Plate 8.15.0 



(1. 1376, 



Diffraction Gratings: see Section "Diffraction of Light". 1377,771 



