Over Johnson pistol

Question
I have a iver Johnson pistol. It looks to be a 32. It is nickel plated, has a hammer on top with a post on top to open. Behind the trigger is a very small, looks like a another small trigger? On the bottom side of the trigger it reads 16478. The grip is black with an owl and when you take it off it has the same number but the letter " N " is now before the same number.  On top of the barrel, Iver Johnson Arms and Cycle Works, Fitchburg.  On the bottom of the grip in metal, the first 3 or 4 letters I cannot make out. After that it reads Apr 6, 86, February 5 (year?), may 10, 87, mar 13, 88 (?) 25, 96.

I have looked every where and cannot determine the Model or year of production. Any assistance would be greatly appreciated, thank you

Answer
Here's a link from wikipedia http://en.wikipedia.org/wiki/Iver_Johnson

The mechanism that looks like a small trigger is actually a part of the trigger mechanism when the gun which is engaged when the gun is fired in single action mode.

There were untold numbers of these guns made. They're not worth anything except as a curiosity.