108 

 *ENGELMANN'S Micro-Spectro-Photometer, No. 191. This apparatus 



designed for quantitative micro-spectrum analysis is constructed on the 

 principle of VIERORDT'S spectro-photometers. 



A short description of the instrument may be obtained on application, in 

 addition to which we would refer to the "Zeitschr. f. wissen. Mikrosk.", vol. V, 

 1888, pp. 289296. 



Price, incl. case: Marks 480. . Code- word: Pepino. 



*Drum fitted with PORRO'S Prisms for erecting the images, No. 192. 



Similarly as in our binocular microscopes of GREENOUGH'S design the PORRO 

 prisms of this eye-piece are encased in a drum, below which is a sleeve fitting 

 the tube of the microscope. A second sleeve on the upper end of the drum 

 takes any eye-piece desired. 



With regard to the use of this instrument on Dissecting Stand P II see p. jy. 

 Price (without eye-piece), incl. case: Marks 40. . Code- word: Pepitoso. 



AMICI Erecting Prism ("prisme redresseur"), No. 193. This prism, 



which is supplied in a mount fitting the eye-piece, besides erecting the image 

 affords the additional advantage of a comfortable position of the head, the optic 

 axis (the direction of vision) being inclined about 30 to the axis of the tube. 



Price, incl. case: Marks 25. . Code-word: Peragrar. 



* Index Eye-pieces. In the course of class demonstrations it is often found 

 desirable to be able to mark any particular point of the object by means of an 

 index. To meet this want we supply the HUYGENIAN eye-pieces 2 and 3, as 

 also compensating eye-piece C in the form of drum eye-pieces with micro- 

 meter (see p. 93) - - fitted with a movable index which can be adjusted laterally 

 by means of a screw in the same manner as a micrometer scale. 



Prices : Code- word : 

 No. 194: HUYGENIAN Eye-piece 2 or 3 with drum and 



index, in case Marks 36. . Peraleda. 



195: Compensating Eye-piece 6 with drum and index, 



in case 49. . Peranton. 



195 a : Index separately, each . /. . Percance. 



Cross-line Eye-pieces. The process of centring the object-stage or the 

 objective by means of special centring appliances requires that the centre of the 

 field should be indicated by a mark in the plane of the diaphragm of the eye- 

 piece. For this purpose we supply glass disks ruled with a cross for dropping 

 into the eye-piece, 



