12 Field Columbian Museum — Geology, Vol. III. 



meters independently and are usually very minute. The appearance 

 of the substance of the crust is like that of black obsidian, being 

 black, opaque and of pitchy luster. The crust adheres firmly 

 throughout to the interior, showing no tendency to scale. There is 

 a noticeable uniformity in the direction in which the threads of 

 fused matter run on the different faces. Such directions are 

 shown in some of the photographs, notably Plates V and VII. 

 In the face shown in Plate VII it is observable that the 

 drift is in the direction of greatest length along the middle line, 

 with diversions to the rear side. If a feather, the barbs of which 

 had been removed from one side of. the midrib, were laid along the 

 surface the directions of the remaining barbs would indicate quite 

 accurately the directions of drift. The drift on this face may there- 

 fore be described as pinnate. On the face shown in Plate V there is 

 drift radiating from the center outwards. On the face shown in 

 Plate VI, or rear side of the meteorite, the drift tends to follow the 

 direction of greatest length, though modified by radiation outward 

 from the pits. 



The crust studied in thin section under the microscope shows 

 nearly all the zones described by Borgstrom. The first, third, and 

 fourth are manifest, but the second zone, or " thin brownish layer," 

 which he describes, is not visible in any of the sections which the writer 

 has examined. The failure of this zone to appear may be due to the 

 thickness of the sections, but if so it would require unusually thin 

 sections to show it. The intervention of the colorless, or third, zone 

 between the dark first and fourth zones is a striking phenomenon 

 and lends a high degree of probability to Borgstrom's view that the 

 fourth zone is due to alteration of interstitial glass rather than to 

 a penetration of molten matter from the surface. The thickness 

 of the several layers, as observed by the writer, accords with that 

 noted by Borgstrom, except in the maximum thicknesses which he 

 quotes. The total crust on the small stone is rarely more than .3 mm. 

 in thickness. Fragments of the meteorite heated B. B. turn black, 

 shading to red distant from the flame and fuse on the edges to a 

 black slag. 



The meteorite as received at the Museum was penetrated by 

 several small cracks extending in a general way at right angles to 

 its broad surfaces. The courses of some of these can be seen in 

 Plate V. Mr. Shields, finder of the meteorite, states that he noticed 

 them the second day after digging the stone up. They probably 

 indicate therefore a partial shattering of the meteorite due to its 



