Slab vs. Quarter, wide vs. fine

[Thomas Erickson]

Originally Posted by Matthew Tucker

the way i see it, the most vertical grain in the middle will strengthen the arch and resist splitting, and the slabbier wood at the flanks adds flexibility at the edges where it is needed.

I'm not so smart when it comes to the physics so I wonder if it's the center/top of the arch that contributes the most to stiffness, as opposed to the whole arch? Seems to me (the layman) like if the bottom of the arch is flexy, then making the top stiff isn't going to do so much good. And then the amount of top-plate area attached to the ribs/blocks inhibiting vibration, in terms of the number of grains... Like I say, I don't know...