---------- Forwarded message ---------
From: Michael Ossipoff <email9648...@gmail.com>
Date: Mon, Apr 3, 2023 at 14:12
Subject: Re: Adjusting dial to new location
To: <kool...@dickkoolish.com>


Of course, but I’d always make the dial to directly show Local True Solar
Time. I’d never incorporate a built-in longitude correction.

My use of EqT & longitude- correction constant is only for:

1. Aligning the dial by use of a clock or watch

2. Getting  Local True Solar Time from a clock or watch

3. Determine the clock-time of a sunset, end of evening civil-twilight, or
beginning of morning nautical-twilight

On Mon, Apr 3, 2023 at 07:35 <kool...@dickkoolish.com> wrote:

> Local Solar Time is one of the things that a dial can do. But I might want
> Time Zone time. Or I might want Paris France time. A dial can do both with
> a longitude correction.
>
>
> ---
>
>
>
> On 2023-04-02 21:40, Michael Ossipoff wrote:
>
>
>
> On Sun, Apr 2, 2023 at 18:31 <kool...@dickkoolish.com> wrote:
>
> I tried the app. I used 40, -75 and 45, -70. It just said to use a 5
> degree wedge and said nothing about a longitude correction.
>
> I communicated to Steve privately last week. I said that a longitude
> correction was a rotation around the gnomon. Does anybody else believe
> this? One of the books, I can't remember which, calls this The Universal
> Sundial Principle. It says that two dials with the same orientation in
> space with respect to the sun will read the same time, regardless of where
> on earth they are.
>
>
> Yes, & if you want Local True Solar Time, then you don't need longitude
> correction or Equation of Time.
> ---
>  If you want clock-time, then use the EqT, & add 4 minutes for each degree
> west of your standard meridian.
>
>
> But isn't Sundial Time (Local True Solar Time) what you want from a
> sundial?
>
>
>
>
>
> On 2023-04-02 19:24, Steve Lelievre wrote:
>
> Jack,
>
> Try out my calculator! You can specify a time zone meridian for the dial
> at its original location, or at its new location, or both. If there is an
> effective longitude change, it'll tell you how to position (twist) the dial
> on the wedge and how to orient the wedge itself, turning it away (rotating
> it ) from the meridian line.
>
> Steve
>
>
> On 2023-04-02 3:59 p.m., Jack Aubert wrote:
>
> I thought about this briefly.  I had always thought that the purpose of
> the shim or wedge adjustment was to tip the dial north or south so that
> dial is at the latitude it was originally designed for.  If the original
> dial has a built-in longitude correction, that could also be factored into
> a wedge which would have both a north-south and east-west axis.  But a
> wedge would not work if it moved the gnomon out of alignment with the with
> the rotation of the earth (or the celestial sphere).  I think a
> longitudinal adjustment would only work if he original dial had a time-zone
> offset included by rotating the hour lines with respect to the origin of
> the gnomon.
>
>
>
> Does this make sense?  It sounds like a good project for a 3-D printer.
>
>
>
> Jack
>
>
>
> *From:* sundial <sundial-boun...@uni-koeln.de>
> <sundial-boun...@uni-koeln.de> *On Behalf Of *Steve Lelievre
> *Sent:* Sunday, April 2, 2023 5:16 PM
> *To:* Michael Ossipoff <email9648...@gmail.com> <email9648...@gmail.com>
> *Cc:* Sundial List <sundial@uni-koeln.de> <sundial@uni-koeln.de>
> *Subject:* Re: Adjusting dial to new location
>
>
> Michael,
>
> Yes, I recognize that to get Mean Time involves Equation of Time
> adjustment and that Equation of Longitude can be handled there to give
> Standard Time (or DST).
>
> But anyway, my inquiry was to seek an online wedge calculator. Nobody
> identified one and  a week seemed an adequate wait for responses, so I've
> just written one.  Anyone who's interested, please see
>
>
> https://sundials.org/index.php/teachers-corner/sundial-construction/367-easy-dial-adjustment-for-your-latitude
>
> Cheers,
>
> Steve
>
>
> On 2023-04-02 1:41 p.m., Michael Ossipoff wrote:
>
> I just want to mention that the shim under the north or south edge of the
> dial is only for latitude. Longitude is corrected-for by changing the
> constant term of the Sundial-Time to Clock-Time conversion.
>
>
> But usually Sundial-Time, Local True Solar Time, is what I'd want from a
> sundial.
>
>
> On Sun, Mar 26, 2023 at 14:30 Steve Lelievre <
> steve.lelievre.can...@gmail.com> wrote:
>
> Hi,
>
> Can anyone point me to an existing online calculator for making a wedge
> to adjust a horizontal dial to a new latitude and longitude?
>
> I am not asking for an explanation of how to do the calculation; I just
> want to be able to point people to a calculator that has already been
> proved on the internet. It should use the original location (latitude
> and longitude) and the new location to calculate the angle of slope of
> the wedge and the required rotation from the meridian.
>
> Many thanks,
>
> Steve
>
>
> ---------------------------------------------------
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
> ---------------------------------------------------
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
> ---------------------------------------------------
> https://lists.uni-koeln.de/mailman/listinfo/sundial
>
>
---------------------------------------------------
https://lists.uni-koeln.de/mailman/listinfo/sundial

Reply via email to