<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> <title></title> </head> <body bgcolor="#ffffff" text="#000000"> Hi Scott I dont think anyone would go so far as to say the board is not a major contributing factor.  Its just that the idea that a change in the vertical displacement of the string by the board / bridge and board assembly can account for much of a change. I look at some obvious consequences of such changes... and these rule out either by virtue of physical realities or by what we observe that vertical displacement changes can account for much.  That basically leaves segment length changes which when accompanying change in tension is calculated become interesting. Even these tho have to add up with what we observe. For example... we see that major changes are happening to the long tenor unwound strings.  So far... there is nothing I've seen put forward by anyone that can account for these changes.  It is stated that the low tension on these wires cause a far greater response to similar changes relative to wire under higher tension.  But you can calculate change in tension for change in segment lengths... and you need a combination of all segments changing lengths pretty significantly to account for the observed change in pitch. One also has to account for why unisons consistently display non uniform change in  pitch to climatic changes... and do so in such symmetric fashion. There is lots we dont really have figured out here... but a strictly vertical displacement just doesnt seem likely.  A  monochord experiment with an adjustable bridge height deflection will underline that nicely for you. Cheers RicB <blockquote> Ok, I get it. Thanks for the clarification. Maybe you guys are right, but it seems counterintuitive to me that the board is not a major contributing factor due to it's size and the fact that it is captured in the rim and has rise and fall (or try too). Is it possible that tension could increase in response to the upward force while also containing the upward movement, or is that impossible? Scott</blockquote> </body> </html>