45, COENHILL, E.G., AND 122, EEGENT STBEET, W., LONDON. 277 



|H|: NEGRETTI ZAMBRA. '"';i!|| 



FIG. 1053*. FIG. 1053. 



POLARISCOPES AND POLARISING APPARATUS. 



Each. Each 



s. d. s. .1. 



1050 Tourmaline Polariscope, elementary form two plates 



of tourmaline arranged in Spring Wire Forceps for 

 holding any crystal to be examined between them, 

 very useful for testing Pebble Lenses in Spectacles . 150 



1051 Reflecting Polariscope, Malus's. The Polarising and 



Analysing bundles are formed of very thin plates of 

 Glass mounted in* brass frames on a metal stand, 

 adjustable at any desired angle. Between these 

 Bundles or Mirrors is a stage for holding Crystals, 

 &c., to be examined, this stage having horizontal 

 movement, with a graduated circle for noting the 

 angle of rotation, &c. ....... 330 



1052 Biot's Improved Black Mirror Polariscope. In this 



instrument Black Glass Mirrors are used instead of 

 the Bundles of Glass, and these Mirrors are fitted with 

 Divided Arcs for adjusting them to any angle. The 

 rotating stage has also a Divided Circle and a spring 

 clip object holder to support the crystals,; &c., under 

 examination. Complete with Tourmaline Plate of 

 Selenite of uniform thickness, Double Image Prism, 

 brass frame for showing polarising structure produced 

 by unequal pressure in a piece of annealed glass, with 

 diaphragm of greyed glass, &c. ; in Cabinet . 7 10 



1053 Woodward's Table Polariscope (fig. 1053), for conve- 



niently illustrating the interesting phenomena of 

 Polarised Light ; fitted either with a Bundle of thin 

 glass or a black mirror. Large and small stage with 

 spring object holder, E/ack-work adjustments to 

 eye-tube, Powers, &c., &c., complete in a Cabinet 

 forming a Stand for the instrument .... 10 10 



Woodward's Polariscope can be supplied for use with the Oxy-Hydrogen 

 Microscope, at a slight additional cost. 



