Comparative penetration of steel and obsidian heads
Repeating the experiment with a 50-pound bow at 10 yards, the results were as follows:
No. 4, target point, rebounds.
No. 5, conical point, enters 4 inches.
No. 6, small bodkin, enters 25 inches.
No. 9, Ishi obsidian, goes completely through.
No. 11, squirrel, enters 4 inches.
Nos. 13 and 14, deer arrows, go completely through.
No. 15, English war arrow, goes completely through.
A 75-pound bow shoots the heavy bodkin, the deer arrows, and the English war arrow completely through.
From this experiment it is apparent that blunt arrows will not penetrate a yielding elastic body of this sort, though we know from experience in hunting that they do pass through small animals, such as the squirrel, rabbit, and fox, passing through either the abdomen or chest. Here, of course, the bony skeleton stiffens the yielding tissues and favors a puncture. It is also apparent that bodkin points are not effective in penetrating soft animal tissues, but that a cutting edge is necessary, and that the broadhead has greater penetrating properties because it cuts a path that relieves friction on the following shaft.
The most striking phenomenon is the great superiority of the obsidian point in cutting animal tissue. Arrows Nos. 8, 9, and 12 are identical in weight, feathering, and size of head, yet the steelheads, even when sharpened to a keen cutting edge, do not approach the penetration of the obsidian by 25 per cent. Doubtless the better cutting qualities of glass, combined with the concoidal edge of the obsidian point, give this superiority. The same principle is used in modern bread knives and roller bandage knives; here a rough wavy edge cuts better than does a straight sharp edge.