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The cable guys were using an artificial horizon to do the time
sights.  I expect it's more precise.  First, they could mount the
sextant on a tripod.  Second, the altitude is half the sextant
reading, doubling the precision.  Third, could use the 12x inverting
scope.  Don't know whether there are additional advantages; they also
_may_ have used a pendulum clock so the observer could time the
conjunctions .  Chauvenet and Wharton & Fields may discuss these
advantages.

Fred
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Frederick V. Hebard, PhD                      Email: mailto:Fred@acf.org
Staff Pathologist, Meadowview Research Farms  Web: http://www.acf.org
American Chestnut Foundation                  Phone: (276) 944-4631
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Meadowview, VA 24361


On Nov 14, 2005, at 10:19 PM, Alexandre E Eremenko wrote:

> Meridian observations
> (with a meridian circle or teodolite)
> need a firm base. But what about time
> sights?
>
> Alex.
>
> On Mon, 14 Nov 2005, Fred Hebard wrote:
>
>> Alex,
>>
>> I would expect they wanted to do some time sights to rate the
>> chronometers.  In addition, (although I'm less sure on this) they may
>> have done some transits to find absolute time.
>>
>> There's a great account of repairing cables in the late 19th century
>> where the fellows go ashore to rate their chronometers.  I can't
>> recall the name nor find the book, but it was mentioned here a few
>> years ago.
>>
>> Fred
>>
>> On Nov 14, 2005, at 7:36 PM, Alexandre E Eremenko wrote:
>>
>>> I am reading a book by a famous Russian XiX century
>>> author, Goncharov, on his voyage to Japan in 1853/4.
>>>
>>> (The Russians were trying to "open" Japan for trade
>>> at that time, the same thing did the Americans (at exactly the same
>>> time).
>>> Japan was "closed to foreigners"; no one could land
>>> etc. I don't want to describe all details.
>>> Anyway, the Russians were negotiating with the Japanese
>>> authorities for a permission to land. The following episode
>>> in this long and complicated negotiation, which lasted several
>>> months, attracted my attention. The Russians asked for a
>>> permission to land on some rock between their ship place
>>> and the land. Apparently a small uninhabited island.
>>> The reason they clamed for this permission was the
>>> "Necessity to check chronometers".
>>> Apparently they thought that this was a good reason
>>> for landing on a rock).
>>>
>>> Unfortunately the author of the book was not interested
>>> in navigation and did not want to explain to the readers
>>> this point. WHY did the Russians think that this was a
>>> legitimate reason?
>>>
>>> Why exactly did they need land to check their chronometers?
>>> Or, more precisely, why did they think that "checking chronometers"
>>> is a legitimate reason for a landing?
>>>
>>> What was the proper procedure of "checking chronometers" they had
>>> in mind?
>>> Was this by the Lunars?
>>> Did they mean that a firm ground
>>> is needed for the Lunars? Or Jupiter satellites? to install a
>>> powerful
>>> telescope?
>>>
>>> (They were at ancor in the Nagasaki harbor at that time. Nagasaki
>>> was one of the few cities where foreigners were permitted to stay
>>> on ancor
>>> at that time). To finish this part of the story I just say that
>>> they were
>>> not permitted. The Japanese quickly built some structure on the
>>> rock,
>>> as an evidence that this rock was "land", rather than some "rock in
>>> the
>>> sea"
>>> or "uninhabited (and unclaimed?) island" where anyone can land.
>>> Before
>>> arriving
>>> to Nagasaki, the Russians signed the paper that they will not land
>>> without
>>> the permission of the authorities.)
>>>
>>> But I only wanted to discuss the CelNav part of the story.
>>> Why did the Russians think that "checking chronometers" was a
>>> legitimate
>>> purpose of landing on a rock?
>>>
>>> Alex.
>>>
>>> P.S. I am well aware that the first underwater transoceanic cable
>>> layings
>>> were made at about the same time. So the Lunars were doomed,
>>> already then,
>>> even as a
>>> mean
>>> of checking chronometers:-(
>>

   

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