Re: Laser Trigon
Hi Alexei, I have built a "lightweight laser trigon" from a laser pointer and some scraps of perspex. As well as producing hour lines and declination lines on arbritrary surfaces, the trigon also has an attachment that allows it to project analemmas about any hour line. I have written up the instrument, and am expecting the article to appear in the next (October) issue of the British Sundial Society Bulletin. I supplied some pictures of the instrument to Bob Terwilliger, which he said he may add to his own version on his web pages: http//www.shadow.net/~bobt/trigon/trigon.htm Regards, John Davis
Re: coordinates
Dear Francois: I ran your coordinates through the mapblaster program and determined that indeed they are for the location of City Hall, downtown. I didn't check other cities, though. In the mapblaster program there is an option similar to your's for which you give mapblaster the name of the city that you want and it gives you a city map with its coordinates. For some reason, the coordinates that mapblaster gives for Tucson are precicely for the entrance gate to Davis Monthan Air Force Base which is several miles from City Hall on the outskirts of Tucson! Thanks so much for getting back to me with your answer, and please excuse my mistake in confusing your program with Fer's. John Carmichael http://www.azstarnet.com/~pappas >Hi John and everybody > >I can give some information about the coordinates of the cities included in >my program Shadows. I took the coordinate from the "Grand Atlas de >geographie de l'Encyclopedie Universalis" published in France. In the >copyright notice they say that it is originally a book from Rand McNally & >Company. > >The coordinates are given for the approximate center of the town. In some >cases, they give the coordinate for another place near the town (i.e. the >Niagara falls: 43*15'N 79*04'W and Niagara Falls city: 43*05'N 79*03'W) but >I included only the coordinates for the town. > >It can't be absolutely accurate, and may be I included also some typing >errors in editing the coordinates for the 750 cities by hand, reading the >book!! > >For Tucson, they only give 32*13'N 110*55'W. > >François Blateyron >EMail: [EMAIL PROTECTED] >Web: http://web.fc-net.fr/frb/sundials/ (cadrans solaires / sundials) > > > >-Message d'origine- >De : John Carmichael <[EMAIL PROTECTED]> >À : sundial@rrz.uni-koeln.de >Date : dimanche 22 août 1999 21:57 >Objet : excuse me Fer > > >>p.s. >> >>I wrote to Fer pleading forgiveness for saying that his program contained a >>list of cities with their coordinates. I was confused and should have said >>that this program is from the "Shadows" program by Francois Blateyron . >But >>I'm still interested in knowing to which exact part of a particular city >>these coordinates apply and how these coordinates were selected. I guess >>I'll have to check out the mapblaster website to find out, now that I've >>made the creators of both these wonderful programs mad at me! >> >>John Carmichael >> >> >> > >
RE: Asop
You wrote: why, in striving to pry into what is in heaven, do you not manage to see what is on earth?' Aesop's Fables Baudelaire was writing about a poet (and an Albatross) but I think it could easily have been an astronomer; or a dialist. Le Poete est semblable au prince des nuees Qui hante la tempete et se rit de l'archer; Exile sur le sol au milieu des huees, Ses ailes de geant l'empechent de marcher. The Poet is like that wild inheritor of the cloud, A rider of storms, above the range of arrows and slings; Exiled on earth, at bay amid the jeering crowd, He cannot walk for his unmanageble wings. Regards, Anthony -Original Message- From: Pace [mailto:[EMAIL PROTECTED] Sent: Thursday, August 05, 1999 5:48 AM To: sundial@rrz.uni-koeln.de Subject: Laser Trigon Hello sundial friends Some time ago I read on some website about a Laser Trigon - which was a laser fitted onto an equatorial axis which I believe simulated the sun and could be used for the projection of the sun rays on any surface. However I have no idea where I saw this and would be grateful if someone knowledgeable about this Laser trigon would give further information about this instrument. Thanks all! Alexei Pace - e-mail: [EMAIL PROTECTED] fax: +1 (603) 853-2666 The Astronomer AN ASTRONOMER used to go out at night to observe the stars. One evening, as he wandered through the suburbs with his whole attention fixed on the sky, he fell accidentally into a deep well. While he lamented and bewailed his sores and bruises, and cried loudly for help, a neighbor ran to the well, and learning what had happened said: "Hark ye, old fellow, why, in striving to pry into what is in heaven, do you not manage to see what is on earth?' Aesop's Fables
Re: Laser Trigon
Alexei > >Some time ago I read on some website about a Laser Trigon - which was a >laser fitted onto an equatorial axis which I believe simulated the sun and >could be used for the projection of the sun rays on any surface. > >However I have no idea where I saw this and would be grateful if someone >knowledgeable about this Laser trigon would give further information about >this instrument. > I designed and made a precision laser trigon to overcome thw problems associated with settimg out hourlines on the conical surface of the 6 metre Silverlink Sundial. See my website address below for a picture of the dial. The instrument is based on a length of heavy-duty aluminium angle which can be placed on the edge of any large square-edged gnomon. Mounted on one end of the angle and truly perpendicular to it is a 3/16" thick brass 'protractor' with precision-reamed holes every 3.75° around its circumference. An aluminium alloy arm, pivotting on a central pin can be set to hours and quarters. The pivot pin is partly milled away so that the arm swings about the interior corner of the angle and hence the true edge of the gnomon style. At the outer end of the arm is a pivotted diode laser arranged so that it can sweep out each hour line from the root of the style to the tip. All bearings are pins held in precision 'vee' grooves by light leaf springs to avoid any possibility of wobble. A tip for the unwary. Do NOT assume that the laser beam is truly coaxial with the exterior of its mounting. Place the housing in a precision vee block and rotate it while watching the spot on a distant wall. If it is truly coaxial (very unlikely) the spot will not move, if not a circle will be described, There are many adjustments to be made to ensure alignment and accuracy which I will not attempt to describe here in words. JPEG of the instrument in use on request. Footnote. After all my care and precision, the gnomon, cast iron and weighing several tons, was delivered rough 'as cast' without the true machined edge which had been promised. A chain is only a strong as its weakest link! :-( Tony Moss == \ ** ** \\ ** ** \\** *** *\\ ** ** *\\ ****** **\\ ***\\ Tony Moss, Lindisfarne Sundials *\\ 43, Windsor Gardens, Bedlington, ***\\Northumberland, England, NE22 5SY, **\\55° 07' 45" N1° 35' 38" W Tel/FAX +1670 823232 Mobile: 07970 208 540 Website: http://www.lindisun.demon.co.uk == The first choice for a Millennium Sundial. (every one Y2K compliant) Horizontal, Vertical, Declining, Analemmatic, Equatorial, Polar and Capuchin Sundials individually made in solid engraving brass. Professional-quality Dialling Scales, 'engine-divided' meridian layout instruments with software. Analemmatic dial plots - any size for any latitude. Graduation, re-cutting and restoration of scales. 'Lintique' patination of brass. ===
Laser Trigon
Hello sundial friends Some time ago I read on some website about a Laser Trigon - which was a laser fitted onto an equatorial axis which I believe simulated the sun and could be used for the projection of the sun rays on any surface. However I have no idea where I saw this and would be grateful if someone knowledgeable about this Laser trigon would give further information about this instrument. Thanks all! Alexei Pace - e-mail: [EMAIL PROTECTED] fax: +1 (603) 853-2666 The Astronomer AN ASTRONOMER used to go out at night to observe the stars. One evening, as he wandered through the suburbs with his whole attention fixed on the sky, he fell accidentally into a deep well. While he lamented and bewailed his sores and bruises, and cried loudly for help, a neighbor ran to the well, and learning what had happened said: "Hark ye, old fellow, why, in striving to pry into what is in heaven, do you not manage to see what is on earth?' Aesop's Fables
