Actually, it means stiffness or the degree of stiffness. Itreally means more than just stiffness; we might say that thisadditional quality is the recovery time, or springiness.
Up until after World War I, spine, as applied to arrows,was an unknown term. No one seems to know just who de-veloped the idea; it seems to be a natural development inarrow evolution. As yet, there is no accepted symbol thatdenotes a given spine. Every good fletcher has had to evolvesome kind of system that works well enough for him but isunderstood by no one else. I made a device which I christenedwith the $10.00 word, "Toxoshaftograph." This worked onthe principle of the weight required to deflect the arrow oneinch when placed on bearings 26 inches apart. I was able towork out a system by which arrows could be spined to fit anygiven bow weight. For instance, for bows from 40 to 45pounds, it required 35 ounces to deflect the arrow 1 inch,and for bows 32 to 35 pounds, it required 30 ounces, etc.
