1955-ish US Navy Periscope Camera Watch with 735A movement

Probably one of the most obscure Hamilton military watches is the Submarine Periscope Camera Watch, part number 39360-2-01.  I couldn't find much about it online, but there are quite a few forum posts about it.  The photos below are from a NAWCC discussion.

What makes the timepiece unique, other than the application it's used for, is the movement that's powering it.  It's a Hamilton 735A.

The Hamilton 735 is the 18 jewel, 8/0 sized sweep second caliber that Hamilton introduced in 1955 to replace the previously used 748 movement.  The primary difference is the introduction of shock jewels to protect the balance on the 735.  Otherwise the calibers share the majority of parts.

So what is the 735A?   Another NAWCC forum post explained there are actually three versions of the 735.  The basic 735 (part number 44011), the 735A (part number 44012), and there's even a 735S (part number 44013), which has a hack feature.  What makes the 735A unique is the specifications that the pallet stones and impulse jewel on the balance were secured with Hysol 250L, the train jewels, train pivots and pallet stones were treated with a special anti-spread compound, and the pallet pivots and lower fourth pivot were not lubricated.  

So there's nothing you'll physically observe that differentiates a 735A, other than perhaps the lack of shellac holding the pallet stones in place.

I recently was contacted by someone who was having a problem with theirs and it was the perfect opportunity to see for myself.

As you can observe in the photos above, the periscope camera watch was presented in a hardened aluminum case with a waterproof crown, similar to the USN BUSHIPS Canteen.  The dial is very similar too but it's not luminous and the watch is not powered by a 987S movement.

My project watch movement came presented in an aftermarket case that has military styling but it's not a military case.  This watch was dropped, hard, and the second hand came off.  It's not running and when I try to set the time the hands don't move as expected.  So something is definitely going on.

As I said, the case looks military but it's a generic aftermarket case.  A case wrench is needed to open it up.

Inside the case is the 735A movement secured by a generic movement ring.  Once I loosen the set lever screw and pull the stem, the assembly will come out the back opening.



The dial is very worn.  I wouldn't be surprised if it was refinished but the luster of the paint is unusual and very chalkboard-like.  The white flecks are actually missing paint chips, not dust or debris.

I do not see the seconds hand pivot sticking out of the center of the movement.  I also don't see any dial feet screws.

The lack of dial foot screws tells me the dial is likely held on by dial dots, or little double-sided adhesive stickers. 

After carefully prying off the dial, I can see the back of the dial is totally flat, there are no dial feet.  I can't even tell where there might have been dial feet before.  The back of the dial is all scratched up.

Sure enough, you can see the remnants of the dial stickers on the surface of the main plate.

The shaft of the center wheel is broken off inside the cannon pinion.  You might be able to see it's still sticking out.  That's why I couldn't set the time, the cannon pinion and the hour wheel were just floating under the dial.

I can see the long pivot of the 4th wheel sticking out of the movement.  I couldn't see it before simply because the cannon pinion was blocking it.

I'll replace the center wheel and hopefully the movement will be good to go again.

I used a small broach to push the remnants of the broken center wheel out of the cannon pinion.

Everything has been cleaned and I replaced the crystal with a fresh one.  Now it's ready to be reassembled.

It doesn't look like it but the movement is ticking away with a nice motion.  I don't have the compounds used originally to lubricate the movement so I just lubricated it like I'd do with any other 735 movement.

It's running nicely, just a little slow.  A tweak or two to the regulator will bring it right in line.

A tweak here, a tweak there, and it's now running just a little fast - that's fine for now.  It will probably settle down after a while.

I'm going to need some fresh dial dots to mount the dial again.  You can see why they're called dots.  The little tan discs are actually covers for the sticky part.  You lift them off, stick them to the main plate and then pull the tan cover off to reveal the other sticky side.

Four ought to do the trick.  Now I just need to center the dial in the right orientation and press it on.

With a fresh crystal, this watch now looks a lot better.  The dial is what it is, there's not much to do about it other than find a better example or custom refinish a dial from a Secometer B.  That model used a 748 so the dial feet would match perfectly.

1927 Cushion Plain

Hamilton's original wrist watch line followed the Henry Ford philosophy... you could have any model you wanted, as long as it was a Cushion.  That lasted for a few years until the line up expanded to add the Square.  It wasn't really just those two choices though.  You could get them in several different versions of solid gold or gold filled.

In 1927 the model line really expanded, and the Barrel was introduced.  All the names were very simple - they referred to the shape of the case.  In addition, you had the option of "plain" or "engraved", which referred to whether or not the bezel was engraved.  So you had six models plus a variety of case materials to choose from.

Even more models came out in 1928 and the list continued to grow, year after year.

1927 also saw the introduced of the "new" 6/0 sized movement that would power most of the models.  The 17 jewel 987.  Shortly thereafter the 979 movement came out, with 19 jewels, and it would be used for the solid gold models (primarily).

The 987 is a very interesting caliber.  It evolved quickly into the 987F, where the jewel settings were friction fit instead of held in place with screws.  In 1935 the 987E was introduced, which was the 987F but with an Elinvar hairspring.  In 1937, the 987A came out and changed a lot of the structure of the caliber but the train wheels and many of the parts where shared with it's predecessors.

For all intents and purposes, Hamilton didn't view the movements as different.  A model that spanned those years could have any of the movements inside and if a early 1930s model came in to the factory for repair, it could leave the factory with a 987A behind the dial - good as new.

You can pretty much completely disassemble a 987, 987F and 987E, mix all the parts together, and reassemble three working movements - although only one of them would have the Elinvar balance.  However, all of the bridges are actually stamped with the movement serial number so you know what parts go with what movement.  It's interesting to come across mismatched bridges in a movement but it happens from time to time.

If you tried to add a 987A to the mix, you'd have a hard time getting it back together if you didn't keep the 987A bridges, etc together, and the shape of the hairspring stud wouldn't fit the earlier 987 balance cock.

So not everything is interchangeable but the complete assemblies are.

The Cushion Plain (or Engraved) changed a little over the years too but it's always the same name.  Earlier models had engraving on the center portion of the case, regardless of it's a plain or engraved model.

Later models the  case center was plain on the plain version.  I think it's interesting that the price difference between the gold filled and solid gold models wasn't dramatically different.  However, $25 in 1928 was a little less than $500 in today's currency.

Working on watches from this era can be very challenging.  I think they are the most temperamental movements that Hamilton made.  They're not bad designs - they were the best the 1920s had to offer.  They are simply really old, really worn, and usually poorly maintained after close to 100 years.  They do not suffer fools graciously - one false move and their delicate parts can break.  Don't drop them, bang them, or otherwise mis-use them like putting them in your golf bag next to a magnetic ball marker.

I like to recall how many old black and white movies have a scene where someone says, "Excuse me, do you have the time?  My watch has stopped."  It happened all the time and there was a watchmaker in just about every jewelry store that stayed very busy.

My project was described as "running fine until it wasn't".  That's not unusual.  It happens all the time.

Looking at it, I can see a few things to note.  First, the dial and hands are a replacement.  They look fine but they're not original.  The crown is a poor choice and doesn't really fit around the stem tube.  It's a later Cushion Plane based on the lack of engraving.  Lastly, it's a green gold (filled) case - which is an interesting color.  It looks like yellow, or natural, gold until you put it next to a yellow gold case - then the difference is more obvious.  You might be able to see the difference in the crown vs the case.

The case back is nicely engraved with a monogram and what looks to be 1932.  Perhaps this watch sat in the store for a while but it was still offered in 1931.

The case is a three piece design with a bezel and a back, each snap onto the case center, which retains the movement and the strap.

Opening up the case reveals a 987F with a very wobbly balance.  I can tell from the balance design that it's not original.  That's not a issue but the fact that it wobbles means the pivots on the balance staff are gone.

There's a white alloy mainspring inside the barrel - so that's good.  It doesn't need to be replaced.

Everything gets cleaned and a replacement balance is readied for installation.  Balance staffs can be replaced but it's a challenging procedure that takes a lot of time.  If I have a working balance, that's usually my first choice.  I know I'm not alone in the perspective - its not unusual to see movements for sale on ebay that are missing the balance.

Everything is reassembled and the balance is ticking away with a nice motion.

It's running a wee-bit fast but I can slow it down with a few tweaks.

Getting warmer.  It will slow a little from here.

The finished watch is outfitted with a proper crown and now looks perfect to my eyes.  This watch doesn't have to be the queen of the showcase but it does have to be treated like the 100 year old precision instrument that it is.   It's a fine watch for dress occasions but shouldn't be exposed to the wear and tear of regular daily use and abuse.  

1958 Sea Crest

It's interesting how sometimes you will find a Hamilton model changes during it's run.  Some models have a long production run - like the 1950s Rodney - it has several different dials.  Other models change bracelets from year to year.

One model that had a subtle change was the 1958 Sea-Crest.  In 1958 and 1959 it had an embossed dial with numerals and markers.

Then, in 1960 and for 1961, the dial changed and was no longer glow in the dark.  It looks like the bracelet also changed.

Mid-run changes like this can make identifying models tricky.

My project watch is an interesting example - it's the earlier dial but it's been customized for use as an award by the Air Force's Air Material Command.

I was told that it was not running well so I decided to put it on the timer.  Normally I don't bother with checking the time before I service it because it really doesn't matter... if it's got a serious issue I'll find out anyway.  Sure enough, it's running poorly... probably very slow but even the timer isn't sure.

The case back is engraved with a presentation for 1st place in the 1959 Tennis Open.  That's pretty cool, huh?  The case back has a prominent lip so you can tell this back will pop off.

Tucked inside is a 17 jewel Hamilton 673 movement.  The inside of the case back has a spring to keep the movement ring and movement in place.

Without the hands in the way, you can see the dial is in great shape.  There's a spec of dust by the 8 but that should come off easily.

Everything is cleaned and ready to be reassembled.

The balance is frozen in time thanks to my camera but in real time it's swinging away with a nice motion.  Now lets see what the timer has to say.

It's running a smidgeon fast.  I should be able to tweak it a bit from here.

There... I'll leave it running 7 seconds seconds fast per day.

The finished watch looks as good as it runs.  I don't think this watch has had much wrist time over the last 65+ years.