Hi, physicsforums! I have a dilemma: there seems to be several strange instruments in our class that nobody is able to identify. The description is as follows: One strip is a brown metal (copper?) and the other is a grey metal (invar? iron?). (I'm making guesses at the metals due to the fact that someone suggested that it could be some bimetallic strip, although the two strips of metal are not welded together.) The strips are connected at one end by two circular fasteners. At the other end of each of the strips are connected two screws. When the two strips are moved together, the screws touch at the ridged end (the one that isn't the cap), similar in fashion to metallic casanets. Can anyone here identify what this instrument is? Thanks!