Hello Mac, The Patent for Porter's reflecting telescope is available directly from the patent office's online site at a huge long url, which is too long to type in or put on a single line. You can just go to: http://patft.uspto.gov/netahtml/PTO/search-bool.html and search for telescope in title and porter in inventor, yielding two patents, one for the refracting, and one for the reflecting one.(having set the full database period in the selection ) The early patents are not in full text, but are fully stored in tiff images. You need a browser plugin for tiff files, AlternaTiff is free and recommended A link is available on the patent site.
>From the drawings and description it appears to have a fairly standard >equatorial mount, further when the prism and ocular are removed, the remaining structure seems sufficient to focus the sun's image on. Again, the declination and HA/RA circles can provide the time. There are locking mechanisms on the declination and latitude rings allowing it to move along the HA/RA circle alone. I'm told there is a 38 page manual that came with the device that included look up tables, but I've not seen it. BTW If anyone has an equatorial mount that is not in use then mounting a mark/extinction pair of tubes or a full 5 set with 4 extinction tubes offset in pairs to both declination and HA/RA could provide a safe sundial application for it. Accurate RA/HA and declination are available from a number of software programs, some free and a number that are low cost. The U.S. Naval Observatory still has ICE (Interactive Computer Ephemeris ) working for free and MICA ( Multiyear Interactive Computer Almanac ) for a low price. I hope this helps! Edley. > Hello Friends, > > The Summer 2007 issue of Vermont Life magazine contains a nice > article on Stellafane, a convention of amateur telescope makers which > convenes each summer in Vermont, USA. > > Prominent among its founders was Russell W. Porter, architect, > artist, mechanical genius, Arctic explorer, telescope maker, and > dialist. > > A sidebar features Porter's Garden Telescope, described as an elegant > combination of a sundial and a reflecting telescope. A replica is > being produced by Fred and Russ Schleipman of Norwich, Vermont. Point > your browser at: > > http://www.gardentelescopes.com/ > > (be sure to read the "History" and "About Us" pages) > > > Porter designed and produced several different cast bronze sundials. > Some may be owned by members of this List. > > My question is, how, exactly, does the elegant device pictured in the > magazine (and on the website) function as a sundial? > > Best wishes, > > Mac Oglesby > > (Who, 60+ years ago, was walking round and round the barrel, trying to > make a reflecting telescope mirror.) > > > > > > > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial >
--------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
