From rkellogg@comcast.net Sun Feb 1 23:12:14 2009 Date: Sun, 1 Feb 2009 23:12:13 -0500 From: Robert Kellogg To: Robert Kellogg , Walter Sanford Cc: Fred Sawyer , Larry McDavid Subject: Re: Jefferson's Spherical Sundial (fwd) All, Found more in the June Compendium 2002... Here's the text: Recreation of Jefferson's Spherical Sundial Monticello, Thomas Jefferson Foundation, Inc.CHARLOTTESVILLE, Va. - A re-creation of a spherical sundial designed by Thomas Jefferson has been installed on the north terrace of Monticello. The device, which features a wooden sphere 10½ inches in diameter, reproduces a sundial made at Monticello sometime between 1809 and 1816. The dial has been placed near where the original stood, based on a description by a visitor to Monticello in 1832. The whereabouts of the original Jefferson sundial is unknown. The design for the re-creation was based on drawings by Jefferson and a detailed description in a letter dated Aug. 27, 1816, to the architect Benjamin Henry Latrobe. Jefferson's sundial was something of a novelty in its time. There is no evidence that spherical dials were in use in North America before Jefferson produced his version, although various types based on the same principle existed in Europe. The re-created sphere has horizontal lines drawn for the Tropic of Cancer, the Equator, and the Tropic of Capricorn. Vertical lines extending from tropic to tropic represent the hours of the day, indicated by Roman numerals below the Tropic of Capricorn. Progressively shorter vertical lines represent half-hour, quarter-hour, and five-minute intervals. The sphere is mounted on a tapered neck with the Equator tilted on an angle based on the location's latitude, 38º 1' North. The noon line is aligned with the true north-south axis. Solar time can be determined by moving the meridian, a bar of thin sheet iron that pivots on the north and south poles. Solar time is indicated when the bar casts the least shadow on the sphere. The device rests on a classical pedestal of Jefferson's design and cast-stone capital modeled on the "corn cob" capitals designed by Latrobe for the old vestibule of the Senate wing in the U.S. Capitol. The original capital, sent by Latrobe as a gift to Jefferson in 1809, has not been located. In an 1817 letter to Latrobe, Jefferson remarked "my dial captivates every body foreign as well as home-bred, as a handsome object & accurate measurer of time." www.monticello.org/press/sundial.html To read Jefferson's own description of the dial, see the note in The Compendium 7(1):20, March 2000. Regards Bob ----- Original Message ----- From: "Robert Kellogg" To: "Walter Sanford" Cc: "Fred Sawyer" ; "Larry McDavid" Sent: Sunday, February 01, 2009 11:03 PM Subject: Re: Jefferson's Spherical Sundial (fwd) > Walter, > > Yes ... but most unusual circumstances. In the master image file held by > Larry McDavid, the enclosed photo is missing. I had it archived in my > original copy of the registy before turning it over to him years ago. > > Larry ... I assume that I did not purloin this photo from some website and > that you pulled for copyright. (I had made a 600x400 rendition for the > egistry MS database... but it's not in the MS Access database !!). > > So Walter and Larry, the photo is enclosed. > > Fred. Seems to me that there was an article about the Jefferson dial in > one > of the Compendiums ... and that a repica was dedicated not only at > Monticello, but one at the American consulate in Italy. > > From the Registry: > > "A replica [now stands at Monticello] of Jefferson's lost dial [made in > 1816], which he recounted in 1817, "My dial captivates every body foreign > as > well as home-bred, as a handsome object & accurate measurer of time." Made > according to Jefferson's design, the dial is a 10 1/2 inch sphere with > horizontal lines drawn for the equator, Tropics of Cancer and Capricorn. > Longitudinal lines are drawn between the two tropics to indicate the > hours > of the day. A gnomon fixed to the poles swings around the globe until it > casts the smallest meridian shadow." > > See: Washington Times December 10, 2001 Metropolitan Section Page B2 > > > Thomas Jefferson's Sundial: Compendium March 2000 p.20 > > "It occurred then [to me] that this globe might be made to perform the > functions of a dial. I ascertained on it two poles, delineated it's > equator > and tropics, described meridians at every 15 degrees from tropic to > tropic, > and shorter portions of meridian intermediately for the half hours, > quarter > hours, and every 5 minutes. I then mounted it on it's neck, with it's axis > parallel to that of the earth by a hole bored in the Nadir of our > latitude, > affixed a meridian of sheet iron, moveable on it's poles, and with it's > plane in that of a great circle, of course presenting it's upper edge to > the > meridian of the heavens corresponding with that on the globe to which it's > lower edge pointed.. Perhaps indeed this may be no novelty. It is one > however to me." > > - Thomas Jefferson > > cti.itc.virginia.edu/~meg3c/classes/tcc313/200Rprojs/jefferson_invent/inve > nt.html > > (graphic by F. deVries is enclosed) > > > > From The Compendium June 2002 > > Cover Issue > > Regards > Bob > > ----- Original Message ----- From: "Walter Sanford" > > To: "Robert Kellogg" > Sent: Sunday, February 01, 2009 7:27 AM > Subject: Re: Jefferson's Spherical Sundial (fwd) > > > > Hey Bob! > > > > Do we (as in NASS) have any info/photos in the Sundial Register re: the > > TJ > > spherical sundial? > > > > ================================================================= > > Walter Sanford, Director Carl Sandburg Middle School > > Center for Sky Awareness 8428 Fort Hunt Road > > Sandburg Planetarium Alexandria, VA 22308 > > Fairfax County Public Schools Work: 703-799-6169 -6197 (fax) > > E-mail: wsanford@wsanford.com Home: 703-765-9392 > > AMS Project ATMOSPHERE Atmospheric Education Resource Agent & > > Water in the Earth System (WES) Resource Teacher > > SCSA, Geosystems, & Camp T-Equity - URL: http://www.wsanford.com/ > > ================================================================= > > > > ---------- Forwarded message ---------- > > Date: Sat, 31 Jan 2009 14:36:00 -0500 > > From: Fred Sawyer > > Reply-To: fwsawyer@aya.yale.edu > > To: Walter Sanford > > Subject: Re: Jefferson's Spherical Sundial > > > > I don't know. It was commissioned by the Thomas Jefferson Foundation > > - they can probably tell you. > > > > On Sat, Jan 31, 2009 at 2:27 PM, Walter Sanford > > wrote: > > > Do you know who fabricated "Jefferson's Spherical Sundial" at > > > Monticello, > > > Fred? > > > [ Part 2, Image/JPEG 44KB. ] [ Unable to print this part. ] [ Part 3, Image/JPEG 655KB. ] [ Unable to print this part. ]