HAMILTON 4992B WWII-era NAVIGATORS CHRONOMETER - MINT! NEAR NOS CONDITION - NON-MILITARY - HALF SEC. PER DAY!! Start Price USD 76.00 Current Price USD 769.00 Time Left - Bid Count 17 Buy It Now Price - Reserve Price - Start Time Friday, September 05, 2008 End Time Monday, September 15, 2008 Location california See more about 'HAMILTON 4992B WWII-era NAVIGATORS CHRONOMETER - MINT!' Description Short story:  HAMILTON 4992B “NAVIGATOR’S CHRONOMETER”,   in mint condition,  carefully twice-tweaked by my expert, and now running like a Hamilton SHOULD run.  In Lancaster, the world’s best watchmakers were not cranking out museum curiosities, and this timepiece was never intended to be treasured away in a drawer, with just an occasional gaze or use.  They made world-class machines, and machines are meant to run.  A high-jeweled, gear-polished, premium lever-escapement movement should make it 250 years of actual run-time (so I have heard), and this one has less than a year of running (my guess), since it left the factory.  My expert repairman (53 years on the bench) put two careful services into it, to get it as good as it can possibly be, and it is freshly lubed for many years of use.  It is nearly as accurate as a quartz movement (more accurate than some), at around a half second per day of irregularity.  It is quite easy to micro-regulate its rate, due to its having a Swan’s-Neck Regulator and a easy-off screw back.  --- so if you get it, USE IT!  Take it to your cubicle or office each workday and hang it at eye level on the wall hook to use as your timepiece all day, and then put it on its rest position at home on the weekends.         The serial number of this 4992B movement places it as being made in 1945 or so, I would guess (4C90000 was 1944, and 4C120000 was 1950, and i would think they were cranking these out ten times as fast in the war years as they did after the war, so this watch, with ser. no. 4C103682, should have been made fairly soon after the 90,000 unit was made in '44).          This particular movement, basically a Hamilton 992B geared for a 24-hour day and with a sweep second hand, is considered one of the best movements ever made.  And this particular example is pristine and is tweaked to optimum.  There are a lot of 4992B’s around, but, in my opinion, less than 1% of them are as good as this one.  One other significant difference in the 4992B/3992B movements (vs. the 992B) is that it has "hack-set" (when you pull out the crown to set the hour/minute hand, the second hand stops, so you can also sync up the second hand correctly and get it back to perfect time);  very, very, few pocket watch-sized timepieces have that feature, and it is especially important on a watch that you intend to make your own dead-on timepiece.         To state an accuracy value, you have to qualify by references to statistical analysis terms.  To see the performance of this piece, look at the last two photos, which show the daily performance over several months.  If you use the methodology given in Hamilton’s manual for their Model 21, which is a bit too liberal in that it “breaks” every five days of run-time, then this 4992B has a standard deviation of under a half second per day during the big majority of the 5-day periods.  But, just look at the graphs and you can pick your own value – if you want, calc. a 2-sigma standard deviation value, breaking it at, say, 30 days, and you’ll still have a jaw-dropping value.   Long Story:         My love of Hamilton wristwatches led me to want to explore just how good their legendary World War II Chronometers were.  So I spent a half year patiently waiting to find NOS or near-NOS examples of their Big Three.  I found excellent examples of the Hamilton Model 22 Marine Chronometer and the Big Kahuna, the Hamilton Model 21 Marine Chronometer.  And I found this 4992B, the most pristine of the trio – nearly NOS in condition.  I knew that I did NOT want a military issue 4992B, since, well, it would have literally been through a war and you can only determine a movement’s max potential if you have one as good as new.  Plus, it looks a lot better not to have the ugly numbers cut into the back.         I then had experts go over them and then ran about ten months of timing trials, with a very, very careful check each 24 hours.  The results of the Model 22 and the 4992B are shown in the last 2 photos.  Each dot is one day’s error, month by month.  Almost every watch sold on Ebay carries the wimp-out caveat that the seller is not saying it keeps time well or that they even checked its time-keeping.  This auction is the polar opposite of that.  Have you ever seen such a record of how well a watch runs?  No pig in a poke here.         On those last 2 photos, each red hash-mark represents a re-regulation done by myself trying to find the right rate for my home environment.  I had a bit of trouble dialing in the Model 22, continuing to over-adjust, and I did not have it quite right for four months.  The 4992B was laid down for three months while I got the 22 right, and I sent it to Mike’s one more time for tweaking.  Then, beginning in August of 2007, I could finally compare them.  And, I found the 4992B to be much better than its reputation and, if you look at the results, you can easily say that it is fully the equal to the Model 22 – and it’s not supposed to be THAT good.  You can also see a correlation in their errors that either means my reference quartz timepiece was actually the cause of the apparent chronometer error, or else both movements were responding similarly to the temperature variations they were encountering as the days progressed.  You can see notes on the ambient temperature written on the graphs.  And the reason that the fourth week of October had no timings is that is when my home town burned to the ground in those fires in San Diego County last year – I was a bit too busy to check them that week.         As an aside, the Model 21 is every bit as good as its reputation, with mine running at under 10 seconds PER YEAR of error!  So, it blew the other two Hamilton chronometers out of the water, but it was not really a contest, since, whereas the Model 22 and the _992B “pocket watch” are surely two of the finest lever-escapement movements ever made, the Model 21 was a fusée-driven spring-detent movement and that is a whole different critter entirely.  I will be selling both my Model 21 and my Model 22 in a month or two.          Since I know anyone scoping out this watch is probably a Hamilton nut, allow me to share a neat photo with you – check the last picture, a group shot of my Model 21, this 4992B, and a Lance I wristwatch (a 770 is inside it).  If you know how tricky it was to sync the second hands of these three timepieces, you'll appreciate this shot – I just about nailed it, as you can see.  HAMILTON RULES!         For this 4992B, the first of the three end photos that I have posted below shows how well each of the two chronometers ran, rest-position by rest-position (DU=dialup, etc.), in six columns, and the reserve listed on the right.  The far left-hand area on that one sheet is the very first month’s running, where you definitely see an almost identical reaction in both chronometers to the day’s getting much warmer as the month of February, 2007, ran by.         However, this piece does have one somewhat aggravating flaw, and it points out the advantage of a subsidiary second hand over a sweep second hand for a chronometer.  I realize that a bomber Navigator and bombardier needed that big obvious second hand for easy reading.  But they sometimes tend to either wobble or to exhibit precession.  This 4992B has a slight precession.  Over an approximate 8-minute cycle, the second hand will go from on to -0.3 second to on to +0.3 second – so the only way to check it to the nearest 0.1 second (which is the precision in which I read it) is to take that once-per-minute time-check for several consecutive minutes to make sure you are registering the middle-point of its precession.  If you do not care that you are possible reading a 0.3 second error into your time-check, then no big deal.  But it did bug me when I had to make a year’s worth of hyper-precise time-checks.  A sweep second hand is NOT the good plan for a chrono.         The 4992B was called a Navigator’s Watch, unofficially, because, like the Model 21 and 22, it was used for precise navigation.  The reason that the shells from a battleship could hit a target’s lat/long coordinates with their first volley from 10 miles out at sea was due to the accuracy of their Chronometer, and one of the Quartermaster’s main duties was to protect it and to use his expertise to deduce the correct time from it’s readings.  However, the 4992B was mainly used in planes and tanks – you could NOT use a Model 21 or 22 in that environment.  It was encased in a shrapnel-proof canister, mounted on shock-absorbing springs to lessen the jolt from flak and the extreme vibrations in a big piston-engined bomber.  However, they went to sea, also.  If you skippered a lowly PT boat, no way would the Navy give you an expensive Model 22, much less a VERY expensive Model 21.  You got a 4992B.  My dad rode out the war in a Sherman (First Armored), but he said that they never gave his crew one of these – but that was because you did not need to “navigate” in Italy or France, whereas the tanks that had to run through wilderness (like the Sahara) did get the 4992B.         My Reserve is only what I have into this remarkable machine.  Considering that to get to this point, it also took patience, luck, and Mike’s great skill to be added to that price makes it a bargain, I think.  If my Reserve is exceeded by $40, then I will throw in the two 10” X 14” World War II vintage magazine pages that you see in the photos.            If my shipping seems pricey, you will get way more than full value for the cost difference.  This will be shipped in a large box, filled with soft shock-absorbing padding – giving it inches of room for deceleration in any direction (there is no substitute for “space” in which to allow deceleration, if you need to lessen shocks – you just cannot get around physics).  My mom was career Post Office, and if you saw the abuse that I have seen in postal distribution centers, you would want nothing less to protect it.           Check out my other auctions – wall-to-wall great stuff.   On Sep-08-08 at 09:29:54 PDT, seller added the following information:I lowered my Reserve by $80, since it seems that I have picked a poor time to be selling anything.  Darn Fannie Mae. 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