392 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1960 



5LAR'ZER 



Figure 3. — A schematic representation of the mechanism whereby we see the disposition 

 of the magnetization with a transparent magnetic crystal. 



appears black. If the analyzer is turned so that the green light going 

 through (a) is extinguished, the region {a) will appear dark red, and 

 (6) will be a pale red or yellow. Kegion (c) will be of some interme- 

 diate shade. Similarly, by turning the analyzer to the other side of 

 the original extinction, setting (6) can be made to appear dark, and 

 (a) light, with (<?) an intermediate shade. Clearly, there is a con- 

 tinuous range of settings possible, and those just mentioned are merely 

 easily defined cases. 



Plate 2 shows photographs of a crystal containing areas of parallel, 

 antiparallel, and transverse magnetization viewed with the analyzer 

 at three different positions. 



Plate 3 is a color photomicrograph showing the distribution of 

 magnetization in a crystal of yttrium iron garnet. The analyzer 

 was set slightly off the original extinction so that it is possible to 

 distinguish between regions in which the magnetization is pointing 

 toward the observ^er from those in which it is pointing away. These 

 are the dark green and yellow bands. The large red bands are re- 

 gions in which the magnetization lies in the plane. Figure 4 shows 

 the disposition of the magnetization in the crystal. 



