In the recent thread ?Problems with bending bamboo? Stephen Selby wrote;
Different growing conditions (for example growing always in the shade or with frequent exposure to sunlight) affects the performance. Some comments in ancient classical Chinese texts suggest that the stiffness of bamboo on one side could vary significantly depending on its exposure to sunlight on that side before cutting.
Stephen, I was surprised when I read the account from the ?Examination of Crafts? (the Rites of Zhou) about the practice of setting the nock slot on cane shafts by floating :shock: the shaft in the water to determine even distribution of the ?shaded? and the ?sunward (the denser?)? side of the cane you mentioned in the book ?Chinese Archery?.
However as the arrow spin and flex during the flight the arrow shaft material shouldn?t vary in density I suppose? It?s very interesting then if this practice (setting the nock at 90 degrees to the floating line) would be really beneficial to the true arrow flight and if the part of the cane floating downwards was actually exposed to the sun.
I apologize for being elaborative on irrelevant subject but I?m very interested if maybe someone can write something more on that matter.
Stephen Selby
I think that the key may lie in the special nature of grasses and the degree of photosynthesis that occurs in the woody stem as contrasted with the leaves.
Evidently, photosynthesis in tree woods is very limited, and such wood with a green bark/skin is normally not selected for working. But selection of bamboo with green active skin is commonplace.
Alternately (or at the same time) bamboo grows in stands with some of the culms permanently shaded from the sun. The sides of culms permanently exposed to sunlight mugh have more drying of the skin, effecting the density (or other quality) of the material.
S
Bede
Assuming that there is some density variation, if the nock was cut perpendicular to the density gradient, then the stiffness would be averaged in the horizontal plane. The arrow flexes most in the horizontal plane when released. Rotation usually doesn't have much effect before the shaft has stopped violently oscillating.
Using a thumb ring moderates the oscillation to a degree, but it is still present. Only experiment can really answer the question of whether this practice is effective. However, I should point out that something doesn't have to have a basis in fact for people to believe it.
Stephen Selby
Noted what Bede says. However, in the late Warring States period (when this notion was recorded) they had a developed understanding of density and specific gravity and their effect on materials. There are many excavated bronze items from the period related to the measurement of specific gravity. Most are assumed to be connected with distillation.
In theory at least, the notion could be scientifically sound. It doesn't seem to be infected with 'yin-yang and five elements' as much of the other literature.
I wonder whether we could get Tom Duvernay to ask a Korean arrow maker to make a selection of cane arrows using the old Chinese method and then compare them scientifically with a control sample from the same maker.
Bede
I think there might be similar ideas in some Middle Eastern works for wooden arrows. I will have a look in the next few days.
I made the disclaimer in my comment because of the well-known and inaccurate belief about left and right handed feathers in the Middle East. There are many opinins that are started with sound observations, but finish with speculation.
