Hi Roger, Any chance you could post pictures of your prototype? Maybe even drawings?
Best wishes, Mac Oglesby >Chris, > >Concerning equatorial tables, people seem to be looking at recent >patents for ELABORATE designs (conical rollers and such). But the >original Poncet table is quite simple. I made my 1977 prototype out >of wood, with a piece of Formica for the inclined plane on which one >end of the table slides. My unit has no curved surfaces at all. > >I've used mine for astrophotography at latitudes other than 42 N >(for which it was constructed). Shoving a small rock under the >north or south end will tilt the whole unit appropriately. I made a >couple of small "alignment wedges" on which I can place a bubble >level for setting the proper base tilt when away from home. I took >it to Turkey for the 1999 eclipse (latitude 39 N) and to the Winter >Star Party in Florida (latitude 25 N) a few years later. The only >restriction is that it won't work too near the Earth's equator. > >I think there's definitely a sundial application here, and I hope to >make one in the coming weeks to show to the list. > > -- Roger > >________________________________________ >From: [EMAIL PROTECTED] [EMAIL PROTECTED] On >Behalf Of Chris Lusby Taylor [EMAIL PROTECTED] >Sent: Tuesday, June 05, 2007 5:30 AM > >This has been an excellent discussion. As several of my designs >purport to be readable to a couple of minutes, I, too, had been >exploring ways to correct for the EoT. > >The Poncet platform rotates the entire sundial about a polar axis, >but has to be made for a specific latitude, so cannot be >mass-produced. A latitude-independent version is described in US >patent 09874026 filed just last year (see >http://www.patentstorm.us/patents/7035005-description.html) Patrick >is correct in saying that if the gnomon has two edges you must >rotate it, not just the dial, as the orientation of the edges would >remain correct, but their position in space would not. > >An alternative that I've investigated is to use two wedges, similar >to those Bill Gottesman uses for the latitude adjustment of his >sundials (also patented: see > http://www.precisionsundials.com/equant%20dial.htm). > >--------------------------------------------------- >https://lists.uni-koeln.de/mailman/listinfo/sundial --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
