A mystery. Solved.

Nothing like a good mystery.

When having dinner with Ted last weekend I mentioned that there was a part in the movement of Nana's clock that I had never seen before. 

When I was first inspecting the movement, right out of the case, I noticed a little piece of curved brass peeking out from behind the back plate and didn't know what it was.

Really didn't pay it much attention to it. Certainly wasn't obvious what it was for and given that it was deeply tucked inside the plates and it was very hard to get any kind of whole view of it.

During the disassembly when I was removing the back plate, I inadvertently captured the mystery thingy in a shot.

Let's call it the Seahorse.

It's a brass piece that is riveted to that back plate. No removing it. 

However it pivots freely on that rivet and has a very large pin sticking out perpendicular to the brass plate. The pin is really like a rod. You can see it protruding clearly 2 photos above.

If you push that bottom round part a little the whole thing swings side to side a little like a pendulum. But of course it's not a pendulum.

I remember wondering about this piece when both initially inspecting the movement and on its first disassembly but, to be honest, I didn't really chase it down at that time.

These photos were not taken as an effort to record the Seahorse. Just good fortune that I take a lot of pictures when working and inspecting movements.

While finishing all the cleaning and such and putting the movement back together, it occurred to me that I hadn't researched this part.

Long story short I looked for some clues in my usual places for quite some time. Nothing I could find.

Nada.

Hmm...

Well I decided to try my best to put it back in place during reassembly and see if I could figure it out. Carefully reviewing my pre-disassembly photos, I aligned it, best I could, as it appeared to me when I first examined the clock.

Here's a photo I used in an earlier post when I was reassembling the movement. The seahorse is lying flat, riveted to the inside of the plate, and the pin is protruding downward as the arrow highlights.

It's really tricking getting all those arbors to line up to their holes on the back plate. 

Where that rod on the Seahorse is supposed to go when the whole piece can pivot around...?

Well...

As I noted in that earlier post, the reassembled movement ran fine so I guess I didn't mess it up.

Furthermore when testing the time train I could not see anything that engaged with it.

I could not think of anything.

What the heck does the Seahorse do? 

What's it for!?

Time heals all wounds.

About two weeks later I was working on the strike train (yeah my day job does making working on this clock rather slow) and researching something entirely non-Seahorse related from some materials I had seen from the great, Dave LaBounty. 

Most of the experts on the NAWCC boards consider Mr. LaBounty as one of the penultimate experts in clockmaking.

If in doubt, ask Dave. 

If you, an expert clockmaker, can't fix it. Send it to Dave.

Dave is a generous and active participant on the boards and I have looked through many examples of his published articles, essays, posts and more when seeking horological insight.

Amongst a short collection of Mr. LaBounty's horological essays was one with the title:

"What is it?"

Intrigued I started to read and within seconds I realized that he was working on a Seth Thomas hip movement just like Nana's clock!

Cool.

Now quoting from the master:

"This question came up a few months ago on the NAWCC Message Board* concerning a strange looking piece loosely attached to the inside of the back plate of a movement. I must admit to posing the same question the first time I ran into “it”. I had disassembled a Seth Thomas hip-style movement, thinking it was just like all of the rest I’d seen. But then I had to get it back together! I can remember the frustration I had trying to get this...thing...arranged and out of the way so “it” would function in any capacity."

WHAT!!!???

Could it be?

No.

Yes.

And here's a copy of an image from his essay:

Yes.

Yes!

YES!!!

Dave LaBounty had the EXACT same mystery experience that I had!

A Seahorse! Or whatever it's really called.

I was floored.

OK I won't keep you in suspense any longer.

A quick primer: 

Almost any clockmaker will tell you that you that when adjusting the time on an old American striking clock you should NOT move hands backwards. It's basically a given that most older American strikers may not respond well / can be damaged by trying to move the hands backwards.

So you don't.

And I would never have tested Nana's reassembled striking movement by moving the hands backwards.

Because you don’t.

Except that is exactly what the Seahorse is for. 

With the Seahorse in place you can move the hands backwards. 

LaBounty never "names" our sea creature but describes it as a lever with a "set-back counter weight."

Wow.

In short, in a movement without a Seahorse, when winding the hands backwards the center lever rod will catch the J lever and can unintentionally hook onto it, snarling (or worse) the striking train. 

The Seahorse lifts the J lever out of the way of the center lever rod when the hands are moved backwards.

I won't go into the all geeky details of the action of our set-back counter weighted lever but Mr. LaBounty's brief essay does a masterful job of explaining this with pictures if you are so inclined.

Mystery solved.