Re: VMs: Identifying VMS stars, and the longitude problem

[jporter@xxxxxxxxxxxx (Julie Porter)]

>>  So you have to be in a certain location to see
>> them.  Solar eclipses also occur every twelve months,
>> alternating each six months with eclipses of the Moon.
>>  They are seen when the Moon is New.
>
>Not quite true, both solar and lunar eclipse can happen twice a year each (two
>nodes of the ecliptic...), and it's conceivable to have a full moon lunar
>eclipse, immediately followed by a new moon solar eclipse.
>
Or Vice versa like this month, where there is a solar next week and a lunar
with the full moon just before Halloween.  Here in the western US the lunar
event happens near sunset.

Note that solar events are localised and only a few see them, weather
permitting. About 1/2 the planet sees a luner eclipse. Also note that the
moon is slowly moving farther away from the earth. This reduces the number
of total events over the course of the centuries. There are three forms of
solar event, Total, annular and partial.  Tradition calls the Metonic cycle
which is a rather good aproximation as the "Dragon." This is a duration of
aprox 18 and 2/3 year. (I have mentioned this and other calinderical cycles
before. None of what seem to be present in the VMS)

I should also point out that was mentioned in passing that Water clocks are
extereamly precice as are sundials. I have not checked the VMS
illustrations for any of the plumbing that looks like a clepsydra yet.
Also note that clepsydra were connected to gears and dials which would show
things like the hand of the dragon. Ref: Su Sung[1:fig 2.9][2][3] and The
anaphoric clock fragment in Salzburg.[1:fig 1.6]

The intereior of a clepsydra is conical. In a high quality clepsydra, the
water exit was set with a jewel to reduce wear on the exit hole.

Clepsydra do not work well in cold climates though, Instead waxed candles
were burned, with markers imbedded into the wax that would fall out after a
precice interval.


-julieP
[1] Geared to the stars. Henry King [1978]
[2] Revolution in time. D. Landes [1983]
[3] History of the hour G. Dorhn-van Rossum Tra. Tho Dunlap [1996]


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