Re:

[Michael Ossipoff]

I wrote:

Hi Franco--
>

Sorry to mis-write your name--I meant Francesco.

48 W
November 20th
1649 UTC
Michael Ossipoff

On Wed, Nov 20, 2019 at 11:29 AM Michael Ossipoff 
wrote:

> My dials will show 9 declination-lines:
>
> 1; Equinoxes, solstices, and half-solstice declinations
>
> 2. Declinations at the ecliptic-longitudes that divide each
> astronomical-quarter (interval between an equinox and a solstice) into
> thirds.
>
> So the dials will indicate solar-declination and solar-ecliptic-longitude
> (expressed in thirds of an astronomical-quarter--the tropical signs of the
> Zodiac, labeled with their traditional astrological symbols for the signs
> of the Zodiac).
>
> The dials will also show Babylonian hours in the morning, and co-Italian
> hours in the afternoon.
>
> The Cylindrical-Equatorial shows h and dec in a clear rectangular format,
> and doesn't need explanation.
>
> The Horizontal Dial or course is the most easily-built stationary dial,
> and is particularly-easily read from any direction by someone who is near
> to it, and tells time whenever the Sun is above the horizon (except if it's
> shaded at some times of day).
>
> A Cylindrical-Equatorial Dial can be built to tell time whenever the Sun
> is above the horizon. The upper edge of the cylinder is trimmed horizontal,
> and the nodus is a bead at the middle of a string transversely across the
> cylinder, with the nodus-bead positioned on the cylinder's axis normal to
> the dial's equator-line.  The nodus-bead is also level with the
> horizontally-trimmed top-edge of the cylinder.
>
> This Cylindricald-Equatorial is similar to the ancient Hemicycleum.
> ...differing from it by using a cylindrical surface instead of a spherical
> surface; using a string-mounted nodus-bead instead of a stick-gnomon (which
> I consider to be an eye-injury-hazard); and not being cut-away as the
> Hemicyclea usually were.
>
> 48 M
> November 20th
> 1628 UTC
> Michael Ossipoff
>
>
>
> On Wed, Nov 20, 2019 at 11:00 AM Michael Ossipoff 
> wrote:
>
>> Hi Franco--
>> .
>> I like explanations that can be understood by anyone from at least
>> pre-secondary-school. I believe that such people can understand the sundial
>> and map-projection explanations that I'd use.
>> .
>> To whom would I give explanations?:  Primarily to my girlfriend. She
>> isn't interested in math, but that doeesn't mean that those explanations
>> wouldn't be understandable to her if she's interested in them, interested
>> in lisening to them.
>> .
>> I mentioned to her that our windowsill sundial would be a
>> Cylindrical-Equatorial Dial, because it doesn't need any explanation,
>> because it shows the Sun's position in the most direct way. She replied
>> that she has nothing against explanation of the Horizontal-Dial, its
>> hour-lines and declination-lines, and considers it interesting.
>> .
>> So the first windowsill dial here will be a Cylindrical-Equatorial Dial,
>> followed by a Horizontal Dial.
>> .
>> In general, I believe that these subjects can be explained to anyone who
>> is interested in hearing the explanation.
>> .
>> So I'd offer these explanations to anyone to whom I'd suggest or offer a
>> sundial or map-projection. I like the idea of a sundial or displayed map
>> being accompanied by a pamphlet or a page that tells its
>> construction-formula derivation-explanation.
>> .
>> Some say that people aren't interested in explanations, but I suggest
>> that, rather, they're often just resigned to things being not explainable
>> to them. I believe that, when shown a sundial or map, they'd like it
>> explained.
>> .
>> It seems to me that every park, library, museum, plaza, and other
>> public-spaces, should have a sundial.
>> .
>>
>> --
>>
>> I'm not familiar with those softare products, but I'd have no objecion to
>> their use.  I'd use drawings, but of course that software could be helpful
>> too, showing things in ways other than what a drawing can show.
>>
>> 48 W
>> November 20th
>> 1600 UTC
>> .
>> Michael Ossipoff
>>
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re:

[Michael Ossipoff]

My dials will show 9 declination-lines:

1; Equinoxes, solstices, and half-solstice declinations

2. Declinations at the ecliptic-longitudes that divide each
astronomical-quarter (interval between an equinox and a solstice) into
thirds.

So the dials will indicate solar-declination and solar-ecliptic-longitude
(expressed in thirds of an astronomical-quarter--the tropical signs of the
Zodiac, labeled with their traditional astrological symbols for the signs
of the Zodiac).

The dials will also show Babylonian hours in the morning, and co-Italian
hours in the afternoon.

The Cylindrical-Equatorial shows h and dec in a clear rectangular format,
and doesn't need explanation.

The Horizontal Dial or course is the most easily-built stationary dial, and
is particularly-easily read from any direction by someone who is near to
it, and tells time whenever the Sun is above the horizon (except if it's
shaded at some times of day).

A Cylindrical-Equatorial Dial can be built to tell time whenever the Sun is
above the horizon. The upper edge of the cylinder is trimmed horizontal,
and the nodus is a bead at the middle of a string transversely across the
cylinder, with the nodus-bead positioned on the cylinder's axis normal to
the dial's equator-line.  The nodus-bead is also level with the
horizontally-trimmed top-edge of the cylinder.

This Cylindricald-Equatorial is similar to the ancient Hemicycleum.
...differing from it by using a cylindrical surface instead of a spherical
surface; using a string-mounted nodus-bead instead of a stick-gnomon (which
I consider to be an eye-injury-hazard); and not being cut-away as the
Hemicyclea usually were.

48 M
November 20th
1628 UTC
Michael Ossipoff



On Wed, Nov 20, 2019 at 11:00 AM Michael Ossipoff 
wrote:

> Hi Franco--
> .
> I like explanations that can be understood by anyone from at least
> pre-secondary-school. I believe that such people can understand the sundial
> and map-projection explanations that I'd use.
> .
> To whom would I give explanations?:  Primarily to my girlfriend. She isn't
> interested in math, but that doeesn't mean that those explanations wouldn't
> be understandable to her if she's interested in them, interested in
> lisening to them.
> .
> I mentioned to her that our windowsill sundial would be a
> Cylindrical-Equatorial Dial, because it doesn't need any explanation,
> because it shows the Sun's position in the most direct way. She replied
> that she has nothing against explanation of the Horizontal-Dial, its
> hour-lines and declination-lines, and considers it interesting.
> .
> So the first windowsill dial here will be a Cylindrical-Equatorial Dial,
> followed by a Horizontal Dial.
> .
> In general, I believe that these subjects can be explained to anyone who
> is interested in hearing the explanation.
> .
> So I'd offer these explanations to anyone to whom I'd suggest or offer a
> sundial or map-projection. I like the idea of a sundial or displayed map
> being accompanied by a pamphlet or a page that tells its
> construction-formula derivation-explanation.
> .
> Some say that people aren't interested in explanations, but I suggest
> that, rather, they're often just resigned to things being not explainable
> to them. I believe that, when shown a sundial or map, they'd like it
> explained.
> .
> It seems to me that every park, library, museum, plaza, and other
> public-spaces, should have a sundial.
> .
>
> --
>
> I'm not familiar with those softare products, but I'd have no objecion to
> their use.  I'd use drawings, but of course that software could be helpful
> too, showing things in ways other than what a drawing can show.
>
> 48 W
> November 20th
> 1600 UTC
> .
> Michael Ossipoff
>
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

Re:

[Michael Ossipoff]

Hi Franco--
.
I like explanations that can be understood by anyone from at least
pre-secondary-school. I believe that such people can understand the sundial
and map-projection explanations that I'd use.
.
To whom would I give explanations?:  Primarily to my girlfriend. She isn't
interested in math, but that doeesn't mean that those explanations wouldn't
be understandable to her if she's interested in them, interested in
lisening to them.
.
I mentioned to her that our windowsill sundial would be a
Cylindrical-Equatorial Dial, because it doesn't need any explanation,
because it shows the Sun's position in the most direct way. She replied
that she has nothing against explanation of the Horizontal-Dial, its
hour-lines and declination-lines, and considers it interesting.
.
So the first windowsill dial here will be a Cylindrical-Equatorial Dial,
followed by a Horizontal Dial.
.
In general, I believe that these subjects can be explained to anyone who is
interested in hearing the explanation.
.
So I'd offer these explanations to anyone to whom I'd suggest or offer a
sundial or map-projection. I like the idea of a sundial or displayed map
being accompanied by a pamphlet or a page that tells its
construction-formula derivation-explanation.
.
Some say that people aren't interested in explanations, but I suggest that,
rather, they're often just resigned to things being not explainable to
them. I believe that, when shown a sundial or map, they'd like it explained.
.
It seems to me that every park, library, museum, plaza, and other
public-spaces, should have a sundial.
.

--

I'm not familiar with those softare products, but I'd have no objecion to
their use.  I'd use drawings, but of course that software could be helpful
too, showing things in ways other than what a drawing can show.

48 W
November 20th
1600 UTC
.
Michael Ossipoff
---
https://lists.uni-koeln.de/mailman/listinfo/sundial

[no subject]

[Francesco Ferro via sundial]

Diese Nachricht wurde eingewickelt um DMARC-kompatibel zu sein. Die
eigentliche Nachricht steht dadurch in einem Anhang.

This message was wrapped to be DMARC compliant. The actual message
text is therefore in an attachment.--- Begin Message ---
I know analytic geometry is the base of any geometric software (though we might 
say that sintetic geometry was the historical base of analisys). What I have 
not understood is the mathematical level of the people to whom you want to 
explain the conic sections, i.e. the daily declination curves. Wouldn't it be 
easier to use some 3d free software like sketchup or geogebra?It is easy to 
draw in 3d the light cones and the corresponding opposite shadow cones. And 
their intersection with any wall or even complex surfaces. And, most important, 
everything is VISIBLE, even to those who are not good in maths.Moreover with 
geogebra 3d the thing is interactive (declination, latitude, inclination ...) 
and you can highlight the involved analitical equations.Francesco Ferro Milone 

Inviato da Yahoo Mail su Android 
 
  Il mer, 20 nov, 2019 alle 12:00, 
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Today's Topics:

  1. Re: Brief explanation/derivation for Horizontal-Dial's
      declination-lines? (Michael Ossipoff)
  2. Re: Brief explanation/derivation for Horizontal-Dial's
      declination-lines? (Michael Ossipoff)
  3. Re: Brief explanation/derivation for Horizontal-Dial's
      declination-lines? (Michael Ossipoff)


--

Message: 1
Date: Tue, 19 Nov 2019 10:25:01 -0500
From: Michael Ossipoff 
To: Frank King , sundial list
    
Subject: Re: Brief explanation/derivation for Horizontal-Dial's
    declination-lines?
Message-ID:
    
Content-Type: text/plain; charset="utf-8"

I've heard that dialists traditionally disregard atmospheric-refraction,
when calculating sunrise an sunset times. That allows the use of
spherical-trigonometry's tangent-formula, instead of the altitude-formula,
a co-ordinate-transformation.

But the orrery derivation of the altitude-formula seems just as easy as the
derivation of spherical-trigonometry's tangent-formula.  In fact, the
orrery-derivations of the alt and az formulas seem, to me, easier.
...even though those formulas are larger than the tangent-formula.

The tangent formula, being briefer, involves less arithmetic, but the
orrery derivation of the alt and az formulas seem more naturally and easily
explained.



By the way, though I'd explain declination-line construction by the
altitude-method, there might be advantage in calculating it by the
trig-at-the-dial method. For one thing, the alt & az formulas can have
subtraction, which can cause a loss of significant digits (which would only
rarely matter, with today's many-digits machines).

Also, if you want the measurement to be straightforward, instead of looking
for the point on the hour line that's the right distance from the sub-nodus
point, which isn't on the hour-lline, then you'd need to calculate the
solar altitude and azimuth both.  That, and the conversion to rectangular
co-ordinates, and then a little work with those co-ordinates, probably
amounts to a bit more arithmetic than the trig-at-the-dial method.

48 Tu
Novembeer 19th
1524 UTC
Michael Ossipoff
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Message: 2
Date: Tue, 19 Nov 2019 10:34:43 -0500
From: Michael Ossipoff 
To: Frank King , sundial list
    
Subject: Re: Brief explanation/derivation for Horizontal-Dial's
    declination-lines?
Message-ID:
    
Content-Type: text/plain; charset="utf-8"

I should mention that, when posting about the trig-at-the-dial method, I
assumed a positive declination. When the declination is negative, you just
use NEO instead of its supplement.

48 Tu
November 19th
1534 UTC
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Message: 3
Date: Tue, 19 Nov 2019 16:03:33 -0500
From: Michael Ossipoff 
To: Frank King , sundial list
    
Subject: Re: Brief explanation/derivation for Horizontal-Dial's
    declination-lines?
Message-ID:
    
Content-Type: text/plain; charset="utf-8"

I said it backwards. For positive declinat