Fwd: Adjusting dial to new location
-- Forwarded message - From: Michael Ossipoff Date: Tue, Apr 4, 2023 at 09:53 Subject: Re: Adjusting dial to new location To: The combination of rotation about the vertical axis, & then non-meridianal tipping, hadn’t occurred to me. …to directly read the Local True Solar Time of somewhere else. …so that you can just use your old EqT plaque after you move? Wouldn’t have occurred to me. I’d just make a table incorporating EqT & the new longitude- correction. I wouldn’t want a sundial to be committed to clock-time, by building in the longitude correction (either when marking the dial, or by the rotation & tipping). On Tue, Apr 4, 2023 at 08:45 wrote: > Rotating the dial plate around a vertical axis is wrong because the hours > lines are not at constant angles. > > Rotating the whole dial around the polar axis is the correct way to adjust > a local solar time dial to a different longitude, the time zone center, for > example. > > Having a dial show the time in a different location is strictly a creative > choice. > --- > > > > On 2023-04-04 08:44, Jack Aubert via sundial wrote: > > 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. > > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Fwd: Adjusting dial to new location
-- Forwarded message - From: Date: Mon, Apr 3, 2023 at 07:35 Subject: Re: Adjusting dial to new location To: Michael Ossipoff 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. When making a sundial intended for use at just one location (e.g. a stationary dial or a portable tablet horizontal dial), I combine EqT & longitude correction into a single correction-table. When all watches were mechanical, & reliable accurate ones were expensive, I used to carry & use a tablet dial, made of corrugated box-cardboard, aligned with a compass embedded in the dial-face. With the combined-correction on the top of the closed tablet-dial. --- On 2023-04-02 21:40, Michael Ossipoff wrote: On Sun, Apr 2, 2023 at 18:31 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 *On Behalf Of *Steve Lelievre *Sent:* Sunday, April 2, 2023 5:16 PM *To:* Michael Ossipoff *Cc:* Sundial List *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
Fwd: Adjusting dial to new location
-- Forwarded message - From: Michael Ossipoff Date: Mon, Apr 3, 2023 at 14:12 Subject: Re: Adjusting dial to new location To: 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 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 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 > *On Behalf Of *Steve Lelievre > *Sent:* Sunday, April 2, 2023 5:16 PM > *To:* Michael Ossipoff > *Cc:* Sundial List > *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 > > > --- >
Fwd: Adjusting dial to new location
-- Forwarded message - From: Michael Ossipoff Date: Mon, Apr 3, 2023 at 14:04 Subject: Re: Adjusting dial to new location To: Rod Wall Yes, because you’ve moved the dial south, you tip it south. The wedge-use is as you say, but I’d prefer a flat, vertical-edge shim, because it wouldn’t experience a force tending to push it out. On Mon, Apr 3, 2023 at 06:45 Rod Wall wrote: > Hi Steve, > > For both examples below with all sundials at the same Longitude. The > instructions indicate: > > Place the wedge-sundial assembly on a horizontal surface in a nice sunny > location. *Start with the higher end of the wedge to the north* and the > sides aligned on a north-south line and the sharp edge should be on an > east-west line. > > Example 1: > > If you have a sundial that was designed for Latitude -20 deg. And relocate > it at Latitude -50 deg. > > Would you start with the higher end of the 30 deg wedge to the North. Or > would it be to the South? > > * > > Example 2: > > If you have a sundial that was designed for Latitude 50 deg. And relocate > it at 20 deg. > > Would you start with the higher end of the 30 deg wedge to the North. Or > would it be to the South? > > * > > Please correct me if I am wrong. I think that both examples would be to > the South. > > Roderick. > > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
