172 Fretp Museum oF Natura. History — Geo.oey, VoL. III. 
besides circular are oval, semicircular, kidney-shape and pear-shape. 
The direction of the cavity tends to be at right angles to the surface, 
but this varies also. Holes similarto these occur in many large iron 
meteorites, such as Chupaderos and Charcas, and are usually ascribed 
to a boring action of the air, or to the fusing out of troilite nodules. 
Their occurrence in the Quinn Canyon meteorite does not seem to 
throw any additional light on their origin. Their existence must be 
more or less responsible for the noise which accompanies the fall of 
a meteorite, for when a current of compressed air is directed against 
one of them a sharp, ear-piercing sound is produced. What the noise 
must be from this cause when the whole mass, highly heated, is ad- 
vancing at an enormous velocity, is almost: beyond comprehension. 
Aside from these coarse features of relief of the surface, there are - 
others of amore minute character. These may be designated as struc- 
ture markings and lines of flow. The structure markings show the inti- 
mate crystal structure of the iron and are most abundant on the walls 
and at the bottom of cavities near the apex of the meteorite. They 
consist of groups of parallel ridges about 1.5 mm. apart, cross-hatched 
by shorter ridges at right angles. Small square pits about Imm. ona 
side are formed asa result. The long ridges are probably formed by 
tenite ribbons. Those at right angles are at irregular intervals, and 
probably mark the crossing of other bands. Asa rule the groups of 
long ridges run in three directions at angles of 60° and often intersect 
to form triangles. The lines of flow as a rule cap the ridges of the 
meteorite and for the most part follow the crests but also at times 
cross them in a series of sinuous, more or less parallel lines. The 
metal is brighter along the lines of flow and in broad patches adjacent 
tothem. They have the appearance therefore of a thin skin of metal 
which has fused and started to flow at various points. The thickness 
of this skin can hardly be more than o.1 mm. The direction of flow 
is always away from the center of the meteorite, or in other words 
from the apex toward the base of the meteorite. 
The pittings on the rear side may be divided into two classes as 
regards size and shape though all are probably similar in origin. The 
pittings of one class are large and circular or oval in outline. One 
of the circular pits is 4 inches (10 cm.) in diameter, and the largest 
oval pit has dimensions of 8 x 8 inches (20 x 13 cm.). Others of the 
large pittings have less regular shapes but all have sharp edges and 
do not merge into one another. The pittings of the other class are 
smaller, dot the surface pretty uniformly and average about one inch 
(2.5 cm.) in diameter.’ They show all variations of shape between 
