Saver Dropouts DEPOSE ER RAVAT

Adjustable drop-outs '30ies.
ER probably referring to Etablissements Ravat. A racebike from the stable Ravat/Wonder.
Also Automoto seems to have experimented with adjustable drop-outs in that period.
In the '80ies Gios had its own version.
And also nowadays there are many forms of adjustable drop-outs in various 
disciplines of cycling.
 

prob