[pianotech] can anyone identify this hardware?

[Ron Nossaman]

On 10/18/2011 4:27 PM, Mark Potter wrote:
>  From an 1884 Vose & Sons upright. Attaches under the keybed - one at
> each end (see closed position photo) . Each pivots outward to extend
> beyond keybed (open position photo). Does anyone know what purpose these
> serve? I can't conjure up a decent guess...
>
> Mark Potter

1884 is early, but perhaps they're locators for a Vorsetzer. Are there 
any obvious wear marks or discolorations on the key tops?
Ron N