Ill 



Latterly we have added to our list a simple form of collective lens of 



about 125 mm (5 in.) focal length, with an iris-diaphragm attached to the 



mount. It stands upon a massive foot and is adjustable in elevation. This 

 appliance helps, not only to produce a better image of the source of light, but 

 also to confine the illuminated portion of the field within sharply defined limits. 

 It is for this reason that it is so well adapted for illumination by means of 

 the vertical illuminator (see p. 36). 



Price : Code-word : 

 No. 201: Collective Lens, with Iris-diaphragm, on stand . Marks jo. . Perdon. 



Spectroscope and Saccharimeter, 



BROWNING'S Hand-Spectroscope. 



This form of spectroscope is fitted with a set of AMICI prisms of great 

 dispersion and is principally intended for the examination of large objects as, 

 for instance, troughs filled with liquid matter. It is supplied in three different 

 patterns, viz: 



No. 202: Without comparison prism, 



Price, incl. case: Marks 40. . 



203: With comparison prism, 



Price, incl. case: Marks 46. . 



204: With scale of wave lengths. 



Price, incl. case: Marks 80. . 

 For particulars of other spectroscopes see our Catalogues of Optical Meas- 

 uring Instruments. 



Hand-Saccharimeter, Fig. 64. 



This instrument is only suitable for fluids containing but a small percentage 

 of -sugar and is principally intended for the rapid and convenient examina- 

 tion of urine. 



Code-words : 

 Perdurar. 



Peregrina. 

 Perenal. 



Fig. 64. Saccharimeter, No. 205. (V, Full Size.) 



