Buying my first chronometer : Thomas Mercer

Welcome to the forum. You are certainly jumping in at the deep end by starting with a chronometer! I can answer your questions by relating to the three specimens I have. +-10s is not particularly good for such a timepiece. Two of mine run consistently within +-2s and one, (a Dent) runs within 1s/day. So yes a service and regulating should show a good improvement. Do bear in mind though that these superb clocks were designed to have a consistent rate rather than maintain precise time.

I know of only one clock maker who specialises in marine chronometers in the UK and he is John Cronin in Stow on the Wold but there will surely be others. Perhaps others will join in the thread and help.

Is your chronometer worth $1500 and will it maintain its value? I'll leave the valuation to others better qualified but I would say that marine chronometrs seem to be one of the few clocks maintaining or rising in value. Please don't buy it as an "investment" though!

 

Hi Dpascal,

John Cronin's website is here. He's a Fellow of the BHI, which is the highest professional qualification achievable in horology. There are other specialist restorers in the UK who can undertake work on these specialised instruments, one of the best of whom is Jon Van de Geer in Salisbury

Regards,

Graham

 

The asking price is reasonable if it as as advertised. Mercer made most of the English chronometers regardless of the name on them so many parts are available if needed.

One thing to keep in mind about box chronometers is that the price depends more on the condition and finish of the box than the instrument inside. I am wary of boxes that still have the top. If the instrument went to sea. the top was usually removed so those with a top are usually either deemed not worthy of sea duty or in refurbished or replaced boxes. If it is an 8 day, it probably has the original top since most of these did not do sea duty.

The rate of the chronometer is of secondary importance compared to its uniformity. If it is ten seconds a day fast or slow, but always ten seconds a day that way; it is probably in decent shape. If the rate varies by more than a few tenths of a second from day to day something is seriously wrong.

If it is merely fast or slow, the rate is adjusted by turning screws on the balance. This is not too hard to do if you know what you are doing; but better left to someone who has done it before and is not a costly process. A full overhaul cleaning and adjustment will be quite a bit more and probably not worth doing unless you intend to run it continuously for a long time. If the detent is bad and it skips (trips) you will do better to return it.

It it varies by more than few half seconds, and it is fast, the instrument is "tripping" and will need repair or replacement of the detent and that will cost as much as you are contemplating paying.

Do not judge a chronometer by its box. I have a very good hamilton in in a badly beaten up box. The box did its job, as did its seals and the instrument inside is in very good condition. Similarly, a beat up bench worn instrument can be put in a new box.

 

Dpascal, I am not a marine chronometer expert, but I only had a nice Hamilton Model 21. I sold it because of these factors:

• It took up too much room, besides which It had an outer box and a huge metal shipping tub.
• I believe these chronometers are meant to be run continuously and can be damaged if they are permitted to run down and stop. That meant that I felt I needed to wind the chronometer every day, which was a chore.
• Even if letting one run down is OK, these chronometers still are a chore to wind, which is supposed to be done at the same time each day.
• It was noisy.
• Because I am not a watchmaker, I need to ship the darn thing to my wachmaker for servicing; safely packing it for shipment was a project. Servicing costs were high even though my chronometer was in excellent shape.

Though usually more expensive than marine chronometers, detent pocket chronometers pose few of these problems. Consider slaking your chronometer thirst with one of those.

I am sure some of you marine chronometer fanciers will disagree with me. So be it.

 

The serial number dates the chronometer to1956/7. It certainly appears to be in a clean condition, albeit that there appears to have been some ham-fisted screwdriver work at some time, and the box appears never to have been fitted with a top lid. What I do see as unusual is that the inner box has no lifting handles. I'm not saying this is a negative point, just I personally have never before seen that style.

The price when new was £126 sterling. (Mercer Chronometers History, Maintenance and Repair. Tony Mercer. Mayfield Books 2003)

 

I suggest that by the 50's chronometer makers had figured out that a top on the box was a bad idea if it was going to be at sea for navigation.

It looks like a very fine instrument.

One other thought however, you might want to take a look at the Russian box chronometers. They are still in production or were until recently and you can buy a complete package (Chronometer inner and outer box) brand new with a rating card for less than the Mercer.

The Russian detent chronometer is a very fine instrument.

If you are going to bring the instrument with you when you return be sure the balance is "Corked" and you know to uncork it. If is to be shipped it will likely also be corked.

They are nice to have around.

 

I have an English one over a hundred years old that was used on a sailing ship that went between Boston and China in the 1840's and it still runs well. There is plenty of power and the pivots are fairly large so there is not much wear on the first few gears in the train.

Look at the side view. The fusee has about 8 levels for about a 54 hour run time. In 24 hours it turns about 3 times a day. The center wheel, under the balance cock, and invisible goes around once per hour, and the third wheel rarely jeweled goes about perhaps 6 times per hour. The fourth wheel is jeweled and it goes around once per minute. The wheels that move more frequently, the escape wheel and the balance are always jeweled.

This is the same jeweling configuration used in all watches when the design of box chronometers was standardized and the English chronometer makers never changed it. Watches really do not need all the jeweling they have but watchmakers were somewhat less hidebound than chronometer makers.

The Russian Chronometers are jeweled a bit more, to the third wheel and the Hamilton model 21 is jeweled to the center wheel.

A 1956 era box chronometer would not be considered through its break in period yet if it had been in continuous service.

They last a long time.

 

I've been an anglophile too ever since my Oxford years, but I'd date the model if my wife dicn't object. To heck with meeting the Queen.

 

Hi,
I have five chronometers in my collection. I have 8 day Mercer, Ulysse Nardin, two russians, one manufactured for the plane the other for the ship and the John Bliss from New York but it is from the before IIWW period. I repair the chronometers and must say that the best is Ulysse Nardin, the next quality are russians next is Mercer .... But I know the Kirov is not British...

You know this film?

 

Most elements of Kirov are gold plated, Mercer is made from the passivated brass... The balance pivot cap in Kirov is from diamond made. 56 hours Mercer costs 1000$ circa, 8 days 5-6... 8 days chronometer is quite different constructed than 56 hours...
Here is my 8 days Mercer...now fully working
Thomas Mercer 8-day chronometer

 

Yes, the same quality... The chronometers named Poljot were manufactured in First Moscow Watch Factory since 1964. Before 1964 it was Kirov... In 1935 the factory was named after the murdered Soviet official Sergiei Kirov...

 

I have a Thomas Mercer chronometer that I inherited in 1999. Runs fine, keeps good time but I’m not running it because I keep forgetting to wind it regularly. Has the double box, lid and glass top on inner box. My late step father in-law had a sailing boat in San Francisco and this clock has been up and down the west coast many times. Peter