THE GEOLOGIST. 
who woiild look at those articles. 
But the same certainty of their 
ori"-iii is not to the inexperienced so 
evident when these flake instruments 
are broken, as they are extremely 
likely to be. They are then, appa- 
rently, only so many ordinary chips; 
but the impress of design clings to 
the smallest fragment, and from a 
chip a quarter of an inch in length 
one could almost speak with cer- 
tainty. The method of manufacture 
of obsidian instruments by the 
Peruvians and South Sea Islanders % 
gives the easiest possible solution 
of the process, which is compara- 
tively easy of accomplishment in ^ 
that mineral, but rather more i, 
difficult in flint, although the method | 
is nevertheless the same in both. 5- 
We will suppose, however, that, the 
savage has got a block of obsidian % 
— he first trims it to an angular form, ^ 
six-sided, eight, ten, or any number g 
of sides will do — thus, (fig. 40.) He & 
then by a series of smart blows struck p 
at each of the corners, a, a, a, (fig. 41,) o 
splits off each of the angles, as long g- 
narrow flakes, broad at the top, and 
tapering away more or less to a point, B 
and having a sharp cutting edge on ^ 
either side, (as marked out by the ^ 
dotted lines,) and characterised by » 
a ridge formed by the angle of the 
block, passing down the front ; the |. 
back being flat or very slightly 
convex. o 
Erom the chipping off of the angles ^ 
the block will assume the shape p 
now indicated, (fig. 42,) its second % 
stage, being still an octagon with o 
the angles or corners all truncated, | 
and presenting a flat ribbon-like band P 
which will characterize the second 
set of flake-knives formed by the 
chipping of these truncated angles. 
It will be seen that the second 
operation reduces the block to its 
primitive form with sharp corners or 
angles; a third operation will restore 
agam the truncated stage, and 
alternately each successive flaking 
will bring about the alternate con-- 
ditions, so that all the flake knives 
obtained by the process will show 
