490 



Refraction. Total Reflection. 



No. 33362 



53 862, 53 859, 53 863. 1 : 6. 



53863. 1:4. 



53,862. Polarisation Apparatus for placing on the Hartl Optical Disc, Figure (Ztschr. f. 



d. phys. 11. chem. U. 19, 1906, p. 105), without glass preparations ......... 2. 8. 



The following can be shown: uniform reflection of ordinary unpolarised Light; Polarisation by 

 Reflection; Polarisation by repeated Refraction; chromatic Polarisation; Phenomena in convergii 

 Polarised Light. 



The apparatus consists of 1 rectangular Sheet Iron Plate fixed on the optical disc; 1 plate 

 Slab and 1 set glass Plates as interchangeable Polarisers; 1 rotary black plate glass Slab as Analyser; 

 1 Stage arranged between the former; 1 small Projection Screen; 1 Condensing Lens for producing 

 converging Light and 1 Sheet Iron Scren for completely shadowing the Projection Screen. 



Fig. 53,862 shows the image when using an unaxial crystal of sodium nitrate. 



53,863. Rapidly annealed Glasses, Figure, for the Hartl Polarisation Apparatus, in wood 



mount, for producing interference images. Each (from selection) o. .!. 



The glasses show in polarised light the inteiference images obtained in Fig. 53,863. Two crossed 

 glasses can also be used (see No. 26a and 27 a in Fig. 53,863): it is advisable in this case to employ 

 the baseplates listed under No. 53,864, which are supplied with a separate mount so as to allow the 

 upper plates to be easily interchanged. 



53,864. Baseplate for Crossed Glasses for producing Interference linages, comprising a rapidlv 

 annealed glass with special wood mount; for use in conjunction with the rapidly annealed 

 glasses listed in the preceding item Kadi (I. 4. <> 



The type of glasses (1) (2) and (7) as per Fig. 53,863 is specially .-unable inr baseplates. l'nle> 

 otherwise stated, triangular baseplate No. -2 is supplied. The mount of the baseplate is provided with 

 special clamps, one of which can easily be loosened so that the upper plate eau lie quickly interchanged. 



53,864 a. Projection Lens for projecting the interference figures on the screen, the si/e of 

 the image being 50 cm diameter. This lens is fitted on the Polarisation Apparatus in 

 place of the small screen o. 4. t> 



C1.3877<1, 3678 '. 



