Table 192. 

 INDEX OF REFRACTION. 



Index ol Retraction of Iceland Spar. 



The determinations of Carvallo, Mascart, and .Sarasin cover a considerable ranRc of wave-lenRtli, and arc here given 

 Many oilier dcterniinalions have been ni.ide, but ihey differ very little from those quoted. 



Smithsonian Tables. 



185 



