74 Dr. Walter Flight — History of Meteorites. 



in breadth, and these in turn are marked with smaller hollows. 

 The whole surface is also covered with three systems of fine parallel 

 lines, forming a network; two of these are at once apparent, the 

 third only after careful inspection : they are Widmannstattian figures 

 developed by the natural oxidation of the surface. The positions 

 of the blunted edges between the shallow cavities are seen to be 

 closely connected with the course of these traversing lines, and the 

 entire meteorite is, as regards its crystallographic characters, formed 

 alike throughout. 



The second side exhibits sharper ridges and a greater number of 

 the smaller hollows, which are only one-fourth or one-third the size 

 of those on the concave surface, and have much steeper sides. Here 

 also is seen the network of lines, still more distinct, and traversing 

 corresponding directions. Two systems intersect at an angle of about 

 70° ; the third, which is only occasionally visible, forms equal angles 

 with the other two. If these lines be sketched, as has been done by 

 Tschermak in his memoir, it becomes apparent that they correspond 

 with a 110 face (rhombic dodecahedral face) on meteoric iron, which 

 in the Widmannstattian figure is an isosceles triangle, with the angle 

 of the apex equal to 70° 32'. The lines or lamella? forming the equal 

 sides of the triangle are perpendicular to the 110 face, while the 

 lamellse of the third system form with the 110 face, angles of 35° 16' 

 and 144° 44. It thus becomes clear why it is that the lines inclined 

 to each other at an angle of 70° stand out so distinctly, while the 

 others are less readily detected : the former meets the cut surface 

 perpendicularly, the latter at a comparatively slight inclination. 



The original surface is gone, but it was probably pitted, and the 

 iron presents the appearance of having at one period formed portion 

 of a larger mass. In the different characters of the hollows on the 

 two sides, it bears a general resemblance to the Agram iron, on 

 which von Widmannstatten in 1808 first developed the figures that 

 bear his name. 



This aerolite, mineralogically considered, contains : iron ; nickel- 

 iron ; schreibersite ; and troilite. 



The iron occurs in three distinct forms : as beam-iron (Balkeneisen) ; 

 as tanite or fillet-iron (Bandeisen) ; and as interstitial iron (Fiilleisen). 1 



The beam-iron is seen on an etched surface in the form of long 

 stripes, which often extend right across it; they are 1 mm. and 

 sometimes 2 mm. in breadth, and occupy the greater part of the 

 surface, traversing it in three directions. One of these intersects 

 a second at an angle of about 83°, and the third at about 97°. If the 

 cut surface were parallel to a cubic face, only two of these directions 

 would be seen, and they would intersect at an angle of 90°. The 

 face of the section, however, happens to lie somewhat out of the 

 plane of the (100) face, and is neaidy parallel to the face of a 

 leucitoid (811), for which face the angles of the trapeze, in Tscher- 

 mak's drawing, are 82° 59' and 97° 1'. 



1 Von Reichenbach distinguished four varieties of iron developed by etching : 

 Balkeneisen, or kamacite ; Bandeisen, or tanite ; Fiilleisen, or plessite ; and Glanz- 

 eisen, or lamprite {Fogg. Ann., cxiv. 99). 



