Too Much Weight!

This balance wheel came out of a watch that happens to take one of two similar hairsprings, of differing strengths.  The movements in this particular family of Elgins are outwardly nearly identical.  Someone used the wrong spring on this one.

To slow down the resulting run-away watch, a very large amount of weight has been added.  Where eight or less timing screws, to each arm, would be typical, this one has a whopping eleven  on both sides!

They're almost all huge screws as well. This thing probably weighs twice what it should.