I've been finally lucky enough to find a Hamilton 37500.
Is there anybody who is able to date it by the serial number? Its serial number is 013195.

Hi Claudio. When you say its serial number is 013195 do you mean the serial number on the data plate on the back of the case, or the movement inside? The number you mention sounds like the number on the back of the case since the Hamilton movements in these should start with 2H. Hamilton made 15,641 of these between 1944 and 1945, so with a number in the 13,195 yours should be from 1945. By the way, Elgin also made these exact same clocks and they made 25,000 of them. The two companies actually made them together in a joint project. Do you have an Elgin to go with your Hamilton yet?

Well, I definitely am not a US military timepieces expert, but I've hunted this kind of clock for years...
Finally I've bought a good one for a reasonable price... I've just paid it and it should arrive soon to me. As soon as received I'll post a little report.
The clock is an Hamilton and the number is from the back of the case. I was sure that Elgin were rarer: you told me a good new!
On the back it bears the Stock no. R88-C-573-II that should mean that it is from US Navy.

I am not sure I would call either the Hamilton nor the Elgin rare - rather I would call them uncommon. I see one or two for auction most every week on Ebay and most seem to have been kept in full working condition. They are the most complicated aircraft clocks the U.S. ever purchased and so there were very few that were thrown away. Also, since they were not made until the last year or so of the war when the U.S. Army Air Force had relative control of the sky there were not so many losses of the aircraft in which they were used so a very large percentage of them seem to have made it through the war. They are not as common as most of the other types of U.S. aircraft clocks, and that combined with the fact that they are complicated and very nice to behold makes them sell for decent prices. On the other hand, I personally think they are much more interesting than some of the deck watches and ship chronometers that sell for three to four times as much so in my opinion they are real bargains even at the going prices. You will need to see the full serial number to tell whether it came from a Navy or Army aircraft. You should find out the last time yours was fully serviced since you would not want to run it for long periods if it has not been serviced lately. If you are a very good watch repair person there is no problem, but if you will need to have it serviced by someone else the cost can be quite high because it is so complicated - perhaps as much as half of what they sell for. There is an Army Air Force technical manual on these that would be needed to do your own servicing.

You're right: those clocks cannot be defined "rare".
Rarity and price depends not only on how they are common, but on how they are sought after and desiderable too.
And they seem to be very sought after and desiderable, not only by collectors, as we will see.
They were very apreciated and they merit their fame.
Since, like you, I don't want to consider them "rare", I haven't bought one until I found one at the right price. And this happened just now.
Anyway we must admit that a version produced in 15.000 pieces is rarer that the version produced in 25.000 pieces. Isn't it?
Anyway I saw much less Elgin than Hamilton...
I find them very desiderable and interesting, I think they could be the most complicated clocks ever mounted on a cockpit.
Lindell... yes: you are right... it is. As soon as received I'll make a report...
Of course, I look forward to receive it... and I cross my fingers...

They are one cool clock.

Some of the Hamilton ones have a brass center push button on lower left dial. They replaced the Jaeger with it's inherent problems.

The fact that they were mounted in every US plane that flew is awsome.

I have seen more Elgins for sell than Hamiltons.

I have both and value the Hamiltons more since I have seen only minor varience between them both.

I am of the opinion that technically speaking there is no real difference in rarity between the two since they were jointly produced with the same parts by Elgin and Hamilton. The way the contract was written, Elgin made the plates, screws and escapement, and Hamilton made the other parts - they then traded parts with each other and both companys put together these model 37500 clocks with the exact same mix of their own parts and the other company's parts. The only real difference between the two are the dial markings and data plate markings where one company's says Hamilton and the other company's says Elgin - otherwise everything else is identical in both of them. It is nice to eventually own one of each to have the set, but they are the same clock with the same mix of Hamilton and Elgin produced parts in all other respects.

Perry, I didn't know that there is that version! It is much rarer, I think!
Do you think that those clock were really mounted in every kind of flying machine, during the war? But, what about CDIA, Type A11 and all the others?
Jim, it is very interesting to hear of the join venture between Elgin and Hamilton: I've read the Withney's book: it dedicates to those clocks many pages... (too many for my english...) and I read only the most technical ones, to understand how they work.

Since many packets from USA to me went "lost" in the past, I'm crossing my fingers, because I really want the clock I bought. Usually , a packet takes 15 days to arrive to me. In Cristmas times, it could take even more. Let's be patient...

The only difference I noticed on my Hamilton is on one of the plates had a jewel on a shaft and the Elgin just had a metal insert. The other one was on the early Hamilton's brass push button.


The 37500's came out and planes were updated with the new navigation clock.

I have seen various cockpit photos with the 37500.

The F7F Tigercat carried a 37500 and a CDIA.

Like anything else when something new came out everyone wanted one.

The 37500 was an excellent navigation clock.

The Jaeger 3920 had a few problems with a single winding spring, date set would bend if date set between 2330 and 2400 as I recall.

The Jaeger's winder also wound in one direction only which would cause problems at times.

The funny part I have seen the 37500 have broken main springs but have not encounterd the 3920 Jaeger breaking one.

The Jaeger has a radio active dial.

The 37500's dial is not radio active but looks like radium.

I tested both with a meter.

My Hamilton came out of the Bar-Bet-II which flew in the Mighty Eighth Air Force.

Please feel free to beat me up if you think any information is incorrect.

If you do I may get motivated enough to take a photo of each.

My favorite is the Jaeger 3920 with the red dial.

The one I have came out of a Martin PBM Flying boat. The red dials were used for navigation and had red hands.

As you recall some CDIA's have red dials and hands.

I talked to a pilot at the Torrance Air Show who flew PBY's in the South Pacific during WWII.

He told me why the hands were red and the minutes were red on the dial.

He said you had to fly in a straight line for a certain number of minutes to do recon and film.
While you were taking photos you were a sitting duck and everyone that was firing at you.

The minute hand was red and the second hand was red, because you did not want to fly one second longer than you had to while flying in a straight line while be shot at.

As best I can remember he said that 3 minutes of flying in a straight line was an eternity.

You are correct all parts on the 37500 are interchangeable.

On the 3920 there is an internal ink stamp dating them on the back case housing inside.

On the 3920 I have seen AF stamps, R88, Navy Anchors.

I was told the 3920 and 37500's were used in B-17's by the navigator.

I was also told the large navigation clocks were frequently stolen.

It has been my observation the 3920 Jaeger keeps more accurate time over the 3920 if not wound for 8 days.

I was also told the reason the luminous dial on
the 37500 was not radioactive. The cockpiits in the bombers had a blacklight on the guages.

Try putting a blacklight to light the luminous dial. It is amazing. The dial looks like the lighted instrument panel on a new Lexus.

The 37500 was the most complicated navigation clock made in WWII. That alone makes it cool.

As far as Jaeger 3920 vs Elgin/Hamilton 37500 it is the 37500 that wins out for reliability.

For a novice like me who has disassembled both and put them together the 37500 was easier.

I ended up calling the Jaeger the clock from ****.

The Jaeger does look more manly and drips testosterone. The 37500 is more intellectual.

So Jim I bow to your superior knowledge.

I think some engineer at Hamilton just thew in an extra jewel to say his clock was cooler.

The same thing happened when Ford and Willys made the WWII Jeep. Ford Jeeps have a F on every bolt.

I am just a simple collector that just has fun with this whole clock collecting experience.

By the way I am looking for a KM Hanhart WWII Watch. (perryandclaire@netzero.com)



Thanks for the discussion.

Thanks, Perry! This is a great treasure chest of comments on the 37500s. I was not aware of the variety that you mention. I wonder whether it is a variety from the factory, and early or late prototype, or the result of repairs? These clocks were high cost items that were repaired rather than thrown away, which is another reason why I believe so many of them have survived to this day. Maybe someone on this forum who is more of an expert on them than myself will know and add their knowledge to this thread.

The story on the red dials is interesting, but I am not sure I see how a red dial would make the kind of difference that pilot referred to as I doubt that a pilot in a combat situation flying a straight line for a photo or bomb run would need to be reminded that straight and level flight is not conducive to keeping your aircraft in one piece. My father was a USAAF squadron commander in the war and he never mentioned it. I've been a pilot for several decades (not during WW II of course) and what a red dial would mean to me is a night vision saving measure. A person's ability to see in the dark increases with the time since they last had white light shining in their eyes. Other colors of light will also reduce your ability to see in the dark but not as much. However, red light is the one color that does little to reduce your night vision.

My clock is finally arrived. I love it.
It works properly: it is very very precise, but the bottom left button doesn't work well... I think that its spring is too weak: as soon as I can I will open it and verify.
Over the top of the case there is a label and a date, over it: MAR 1953.
Does anybody know what it does mean???

Can you post a photo of the marking? Usually these kinds of markings are the result of the clock being serviced by a U.S. military watchmaker. The U.S. military used to have their own soldiers who were trained as watchmakers and repairmen who worked in several centralized service centers that did the repairs on their clocks and other instruments. After doing repairs or servicing on clocks or other instruments they often marked the outside of the case with a date that indicates when that particular servicing or repair was completed. This is different from what most private watchmakers do when they scratch such things in small letters and numbers on the inside of a case where no one will see it. In the U.S. military no one wanted to bother having to open up a clock and search for such markings - they wanted everyone to easily tell the last time a clock was serviced by quickly looking at the outside. Sometimes these are done on removeable paper tags which is why you do not see such markings on most clocks and watches, sometimes it was done on a paper label that was glued to the case and in many cases these paper labels have since been removed, and sometimes the markings were applied directly to the outside of the case with paint (usually white or yellow paint) using with a rubber stamp. Many less informed collectors remove such markings since they do not know what they are or they do not want people to think their clock or watch is not as old as it is or they think it detracts from the nice clean look that they would prefer. It is part of the history of the clock or watch in my mind.

My initial guess without seeing the marking is that your 'MAR 1953' marking is simply one of these notations by an Army or Navy servicing center that they did a repair or servicing in March of 1953.

Thanks Jim!
I agree: I think that the label could be a record of a service job too, and I think that it must be left there, too.
I will post the scans as soon as possible: during next weekend I will make some shots...

Finally at home, observing the label: it is readable, but not easily, it seems to say: "date of overhaul", but the date and the code of the operator are overwritten just over this writings, so not too clearly understandable. A scan will follow ASAP.

Anyway, I've opened the case: I've never seen a dirtier movement, but it works great and keeps perfect time!! It cointained even a small dead mosquito, at least 20-30 years old! But it goes!
The last watchmaker who serviced it used a grey graese in some parts, like the column weel and the connections of the two knobs stems... I don't like this choice... Any experts' opinions?

Like all the good students, after dinner, I made my homework...
The botton left knob wasn't working because someone did mount it in a wrong way: the spring and the washers have had been mounted under the frame: this made its operation impossible!
Observing the Withney's book I understood that they have to be mounted AFTER having mounted the frame and outside it. Now everythings work properly.
At the end... I went to bed at 01.30 a.m...., but I saved some money instead of going to the watchmaker...

The serial number on the movement is 2H14993... any informations about the date of production, sirs? I suppose this confirms: 1945. Am I wrong?
Thanks, Claudio.

Here is the image of the label.
On the top of it there is "NAS SEATTLE" that should stand for "Naval Air Station": here a pair of links about it... (interesting... isn't it?).

http://www.historylink.org/ind...put.cfm&file_id=2249

http://www.history.navy.mil/ph...af-amer/seatl-st.htm

As you can see, under this writing there are three smaller boxes: the first, in the left one there is written "OVER HAUL", in the center one "MECH", in the right one "INSP".
Over all there is the ink stamp: "WEJ", then "85" in a circle and "MAR 1953".
So it could have been overhauled by the mechanic WEJ and inspected by the inspector "85"...
Any opinions? thanks, Claudio.

Yes, Claudio, I believe you are correct in your interpretaion of the markings.