"K.V.W.S." in Wheatstone Ledgers

[arkwright]

In the Wheatstone Ledgers, some concertinas are tagged "K.V.W.S."   Does anyone know what that means?

[Geoff Wooff]

Key  Valve  and  Wrist  Straps.   

 

Prior to  the  air  button  being  operated  by  a  "Key"  there  was  a " Slide Valve"   a  lever  that  the  thumb  actuated  with  a  sideways  movement  (S.V.)  .   

 

 

Edited March 1, 2021 by Geoff Wooff

[arkwright]

Thank you!

[Mike Franch]

And, to my mind, the S.V. was much more convenient that the air button, but that's probably off topic.