My responses are interspersed below.
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From: "Frank King" <[email protected]>
Sent: Friday, April 02, 2010 10:18 AM
To: "Roger Bailey" <[email protected]>
Cc: "Gianni Ferrari" <[email protected]>; "Frank King"
<[email protected]>; "LISTA INGLESE" <[email protected]>;
<[email protected]>
Subject: Re: how italian hours
> Dear Roger,
>
> You are right...
>
>> This gets more interesting with each note.
>
> The business of labelling gnomonic features
> elegantly can be a nightmare!
>
> With an ordinary sundial you have a chapter
> ring of one kind or another for the labels of
> the hour-lines and life is straightforward!
>
> When you try to label Babylonian hours and
> Italian hours it is easy to get into a mess.
>
> [You especially get into a mess if you
> insist on using Roman Numerals. A time
> like XVIII takes up a lot of space!]
On the Istanbul sundials they only put numbers on the Italian hours. Those
hours go to 12 at sunset as they use two 12 hour cycles' The French hours
are numbered but this is on a different scale around the outside of the
dial. They do not use our Arabic numbers. That would be too easy. They use
Indo-Turk numerals that can be confusing.
The Al Shatir dial dated 1371 in Damascus has Italian hours for the
afternoon and Babylonian hours for the morning.
>
> You say that...
>
>> ... on the sundials in Istanbul, Topkapi
>> Palace ... they assigned 6 to noon. On
>> the equinox all the lines cross the meridian
>> at 6. The others then fall into place.
>
> This certainly makes things easier but could
> you confirm my interpretation of what you
> are saying?
>
> Are you saying that at the crossing point,
> on the equinoctial line, at one hour before
> noon, they number the four times:
>
> Babylonian = 5 Yes, 5 hours from dawn
> French = 5 No because the polar gnomon and point gnomon are not the
> same.
The point gnomon is half the height of the
polar gnomon directly above it
> Italian = 5 Yes as it 7 hours to sunset and 12-7=5
> Temporary = 5 Yes, 5 hours from dawn
>
>
> Clearly Babylonian and Temporary would be
> called 5 anyway but not French and Italian.
>
> Have I misunderstood?
>
>> The horizontal 12 line on the south facing
>> dial is interesting.
>
> Sorry. I am lost here! Is this the line
> which I would call Italian = 24 but which
> is now being numbered 12 because it is 6
> at equinoctial noon? Yes but not because noon is 6 but because sunset is
> 12, not 24
>
>> In Istanbul they used two 12 hour cycles
>> so there were no numbers in the teens and
>> twenties.
>
> Given your assertion that noon = 6 are you
> saying that when there are 14 hours of
> daylight the French hours are numbered:
>
> 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 Yes, just as we go through noon
> as 11 12 1 but we could go 11 12 13 with a 24 hour clock
>
> Also, do they use *real* Arabic numerals? No a Indo-Turk or Eastern
> Arabic. See http://en.wikipedia.org/wiki/Ottoman_Turkish_alphabet
>
> Very best wishes
>
> Frank
>
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