Fusion- structures in M.teorites. 295 



that greatly resembles that of a shell-strnctare, presenting un- 

 der 300 T). power even a slightly curved face. Figure 3 is the 

 upper left-hand ])arl; of the same structure, but magnified 

 1,500 D. Bringing so high a power to bear on the object, the 

 latter loses the columnar appearance it shows under lower 

 powers, and now looks liki-- a terrestrial trap-formation. Later 

 on reference will again be made to this structure. 



Figure 3, occurs in the same section, and shows the fusion- 

 bars grouped, but more parallel to each other and not exhibit- 

 ing the tendency to converge to a point, as in Fig. 1. 



Figures 4, 5 and 6, same plate, represent a different type of 

 fusion-structures. In all these the bars are so small, that 

 needles would, in these cases, be a more appropriate term ; yet 

 they very decidedly evince the tendency to converge at an 

 angle. 



Figures 4 and 5 are magnified 300 D. ; Fig. 6, however, 

 from a different meteorite (14, Slide 23), is magnified only 

 75 D. 



Figures 7, 8 and 9 fully illustrate the type of the mineral 

 substance scattered through the metal ; Fig. 7, showing the 

 convergence-tendency before noticed ; Fig. 9, a parallel disposi- 

 tion of the bars ; Avhile in Fig. 8 these bars have assumed a more 

 curved form. 



In Plate XX, Fig. 3 disiDlays the same curved apj)earauce, 

 hut only in part — the lower portion of the structure showing the 

 angular convergence of the needles ; Fig. 2 is to illustrate the 

 sharp point to which sometimes the bars are drawn ; which 

 same feature one of the structures in Fig. 1 exhibits. 



Figs. 4, 5 and 6 need not be further discussed. Figures 7, 8 

 and 9 are treated of in detail further on, being intended to de- 

 monstrate the action of fusion which meteorites suffer on their 

 surface in traveling through the air-envelope surrounding the 

 earth. 



These structures are nearly all magnified 300 D. ; some, how- 

 ever, only 75 or 150 D., the exact number is in each instance 

 given in the Plate Index. 



All these fusion-structures polarize light ; some, however, 

 more than others. 



In studying the effect of polarized light on these formations, 



