107 



The distance between the eye-pieces is adjustable by altering the position 

 of one of the eye-piece tubes - - to suit the intra-pupillary range of any indi- 

 vidual observer's eyes. The instrument is available (but in conjunction with 

 achromatic objectives only) for use on any of our large stands in which the tubes 

 admit of shortening to at least 140 mm (5y 2 in.). 



No. 189: ABBE's Stereoscopic Eye-piece, Price, incl. case Mk. 180. . Code-word: Peonia. 



* ABBE'S Spectroscopic Eye- piece (Micro -Spectroscope), No. 190, 



Fig. 61. 



This eye-piece is specially designed for the examination of the absorption 

 spectra of microscopic objects, but is also adapted for spectroscopic analysis of 

 larger objects, liquid strata, &c. 



The achromatic eye-lens is accurately adjustable with respect to the slit 

 situated in the plane of the diaphragm. By a lever arrangement a comparison 

 prism can be applied to the slit to facilitate spectroscopic comparison of the object 

 with other absorption media, which are attached in suitable holders at the side of 

 the eye-piece. An assortment of small glass tubes is supplied for this purpose. 



Fig. 61. ABBE'S Micro-Spectroscope, No. 190. 



Longitudinal section of the whole Slit Mechanism separately, 



instrument. ( l / 2 Full Size.) (Plan view, Full Size.) 



A direct- vision AMICI prism, which may be turned aside about a pivot, 

 is placed above the eye-piece. A scale of wave-lengths is projected upon the 

 spectrum by means of a tube, with mirror and lens, attached at the side of 

 the prism casing. 



The instrument is inserted in the tube in place of the ordinary eye-piece. 



For fuller particulars regarding its construction see the directions accom- 

 panying the instrument. 



No. 190: ABBE's Spectroscopic Eye-piece, incl. case . Mk. 200. . Code-word: Peorus. 



