Missed Base

Question
Here's the situation: Two runners, Smith and Jones, are on base.
The batter singles and the two runners score. Smith, the lead
runner, comes in first but fails to touch home plate. Jones, the
following runner, does touch the plate. Does the umpire
immediately, on his own initiative, declare Jones "out" for passing
Smith? Or does he remain silent until the defensive team executes a
proper appeal on Smith's failure to touch? Moreover, if such an
appeal is executed and successful, how many runners are out?
Smith alone, for failing to touch, or Smith and Jones, one for failing
to touch and the other for passing the runner ahead of him?

Answer
Paul,

This is an appeal play, so the umpire will do nothing until the defensive team appeals.  The only runner who would be out on the appeal would be the first runner.  If that is not the third out, then the run of the second runner would count.  If it is the third out, then the run of the second runner would not count.

Also, this play must be appealed before the next pitch.  If a pitch is made, then the play stands and no appeal is then allowed.

Hope this helps!

Brian