566 



Gale-spar and Quartz Preparations. 



No. 54 760 



54 776. 1 : 2. 



54777. 



3. 



54 785. 



Clan's Prisms (M. P. II, 1, Fig. 854 [1018]), with air stratum, without cement, optical axis 

 parallel to refracting edge, end surfaces perpendicular to direction of rays: 



List No. 54,760 54,761 54,762 



Free Aperture 12 16 20 mm 



1.4.0 1.16.0 3.6.0 



54.763. Wild's Double Plate 



54.764. Calderon's Double Plate 



54.765. Three Different Calc-spar Rhombohedra, Figure, with 6, 8 and 10 polished sur- 

 faces, 20 mm side, in case 



Rhombohedra with the 6 natural cleavage surfaces, all 6 surfaces polished: 



List No. 54,766 54,767 54,768 



Side mm 20 25 27 



0.16.0 1.6.0 1.15.0 



- idem, also having two surfaces (ground and polished) perpendicular to the axis (8 polished 



surfaces). List No. 54,769 54,770 54,771 



Side mm 20 25 27 



1.0.0 1.12.0 2.5.0 



- idem, each having in addition two ground and polished surfaces perpendicular and parallel 



to the axis (10 polished surfaces). 



List No. 54,772 54,773 54,774 



Side mm 20 25 27 



1.4.0 1.16.0 2.10.0 



54.775. Calc-spar Cube, ground perpendicular and parallel to the axis 



54.776. Calc-spar Plate between two Glass Prisms, Figure, shewing from one side the 

 ring system and from the other double-refraction 



52.224. Press for producing the sliding surfaces in calc-spar and rock salt, after Reusch, with 

 preparations 



52.225. Pressed and unpressed Preparations, singly 0. 2. 6 to 



52.226. Press after Baumliauer, for producing calc-spar doublets . 



54.777. 2 Large Calc-spar Rhombohedra on stands, Figure, in mount, rotary, approx. 

 25 mm side, for demonstrating all phenomena of double-refraction and polarisation 

 peculiar to calc-spar 



Quartz Preparations. 



Quartz and Rock Crystal Prisms: sec Nos. 53, 975 53,986. 



Quartz Lenses, bi-c<mve\, perpendicular to axis, in two different radii of curvature, 300 or 

 150 mm, first quality: 



54,778 54,779 54,780 54,781 54,782 



40 45 50 (ill 7<> 



0.15.0 1.0.0 1.5.0 1.10.0 2.0.0 



List No. 

 Diameter inn; 

 



54,78/5. Double Plate, of right and left rotating quart/, 

 54,784. Bertrand's quadruple Quartz Plate 



6. 0.0 



0. 1L'. (I 



1. -4.0 



CI. 1858, 



3873, 1058', lii.v.l. 



