140 



MICRO-SPECTROSCOPE AND POLAR/SCOPE [CH. VI 



for the ocular micrometer (§ 172). If one now uses daylight there 

 will be seen in the spectrum the dark Fraunhofer lines (Fig. 121 E. F., 

 etc.). 



Fig. 12- 



Fig. 124. 



Fig. 125. 



Fig 123. ( 1). Section of the tube and stage of the microscope with the spectral 

 ocular or micro-spectroscope in position. 



Amici Prism ($ iSS). — The direct vision prism of Amici in which the central 

 shaded p> ism of flint glass gives the dispersion or separation into colors, while the 



