00 



oo 



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

 prism casing. 



For fuller particulars regarding its construction see the directions accom- 

 panying the instrument. 



Nos. 191 and 191". *ENGELMANN'S Micro-spectro-photometer. This 



apparatus - designed for quantitative micro-spectrum analysis - is con- 

 structed on the principle of VIERORDT'S spectro-photometers. The Apparatus 

 No. 191 is provided with prisms, No. 191" with grating for the production of the 

 spectrum. 



As to the use of the apparatus we would refer to the instructions given in 

 Zeitschr. f. wiss. Mikrosk., vol. V, 1888, pp. 289296 and Sitzungsber. d. Berl. 

 Akad., vol. XXXII, 1902, pp. 706710. 



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



Similarly as in our image erecting microscopes the PORRO prisms of this ocular 

 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 ocular desired. 



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



which is supplied in a mount fitting the ocular, besides erecting the image affords 

 the additional advantage of a comfortable position of the head, the optical axis 

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



Nos. 194 and 195. *lndex-Oculars. 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 oculars 2 

 and 3, as also compensating ocular 6 - - in the form of drum oculars with micro- 

 meter (see' p. 76) - fitted with a movable index, No. 195", which can be 

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



