NavList:

Dear George and Coralline Algae,

I am not an expert in marine chronometers,
but I am following them on e-bay last month
(just out of curiosity). I am afraid that
$1500 is not enough, unless you want a Russian one.

Here is the recent statistics:
English 1865 chronometer by Brown $5211
Thomas Mercer in fair condition (possibly not working) $986
Thomas Mercer is good condition $4,626
Thomas Mercer in good condition $3,728
John Pool chronometer in good condition $3,250
Russian "Polet" from Russian seller $810.

As I understand, Thomas Mercer was the common British
chronometer in WWII. They (and American Hamiltons) are
most frequently seen on e-bay. I've seen an advertisement
of Wempe, the only Westren company I know that makes mechanical
chronometers now. It costs about $10,000.

Of course, chronometers have nothing to do with
the "time of Newton", not speaking of the "time of Kepler".
Navigation at the time of Kepler used astrolabia for the Sun and
cross-staff for the Polaris, while at the time of Newton, the most
advanced technology was the Davis backstaff.

By the way, a backstaff is made entirely of wood, and I can imagine
that a decent one can be made by some very advanced amator even
in modern time:-) Has anyone ever tried to make a good working replica?


Alex

On Mon, 15 May 2006, George Huxtable wrote:

> "As part of my plan to immerse myself in the time of kepler, newton
> with respect to navigation and other things.  I have been researching
> mechanical watches and chronometers. "
>
> Well, Kepler's (and Tycho's before him) great misfortune was that they
> lived before the era of accurate clocks. Otherwise, their observations
> could have been much more precise. Instead, they had to resort to
> complex stratagems to deduce time, such as by the altitudes of
> celestial bodies: the same set of bodies for which they was trying to
> determine the positions.
>
> As for Newton, though he lived in the period in which pendulum clocks
> and balance-spring watches were being developed, a practical seagoing
> timepiece did not emerge until 50 years after his death.
>
> Nevertheless, Coralline Algae's aim is a noble one.
>
> I wonder if the purchase of a secondhand marine chronometer, in a
> gimballed box, has been considered? Thousands of these instruments
> were in use at sea, often in sets-of-three. They may seem expensive
> now, usually sold as "antiques", but nothing compared with the outlay
> of $1500 that is being contemplated. That would seem more in keeping
> with the research intention, than an expensive Russian tick-tock. The
> main problem might be to find a craftsman to put the instrument in
> proper order, which might well call for no more than knowing where
> (and where not) to apply a tiny drop of oil. And keeping it out of the
> hands of those that don't know.
>
> Not that I claim to have any special knowledge about marine
> chronometers. Geoffrey Kolbe's advice is sound.
>
> George.
>
> contact George Huxtable at george@huxtable.u-net.com
> or at +44 1865 820222 (from UK, 01865 820222)
> or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
>
>
> >


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