Dear Fellows in sundialling
Based on certain accidental discoveries I had made yesterday, I waked up a little earlier this morning and walked to my back yeard to prepare for the sun to rise above the ceiling of a house south to mine. Rounded off, 7 o'clock was the time when I should be there. Nevertheless, I had to do some preparations in advance for it was only 6 when I was in position selecting the tools I would need soon. I made sure I had available an engineering compass, a big ruler (2 m long), protractor, set-square and a pen with indelible ink. I had everything handy. It was only a quarter past 6. I went back to the house, got a shower, reviewed some annotations. At 7 o'clock I was back in the spot I had prepared. In the ceramic floor there was a North-South line drawn in the weekend. I drew it when I was calculating a vertical inclining dial. I had to calculate the inclination and the quickest way I could figure out in that moment was to use the noon time that was approaching. I found information about the equation of time, calculated the hour angle, put a big nail in a table and when my wrist watch told me the sun was northing I drew the line. Since declination was around -4 and I my house is around -15 the shadow was not big, but enough for me to have a reasonable North-South line. With a engineering compass I double checked it and found that even adding together the possible compass error (after applying the correction for about 19.5 d for magnetic declination) plus my own inexperience in using such a device, the total error would not be greater than 2 degrees. Good enough, for the time being. Now I was there, steping on a North-South line, facing the rising sun whose Azimuth was... 90 degrees. I put the ruler in the ground, crossing the N-S line. Than I moved it until its shadow was completely hidden under itself. Than I put side by side with it a square piece of wood in whose center a tall nail was half-driven. Wonder of the wonders! The shadow cast by the nail was completely parallel with the ruller and this, by its turn, made a perfect right-angle with the N-S line, as shown by the set-square. In that moment I felt a enourmous pleasure. I pleasure that I think only children usually have. I had mastered the millenary art of understanding how the sun moves across the heavens. I wanted to share with you that vivid moment of sheer joy. Something completely childish. An accomplishment that does not have any practical purpose; the act of doing something that any one with just a modicum of trignometry could easily do; a finding that does not add anything to anybody in this world. Notwithstanding, I was so happy! Becoming involved with sundialling has given me the opportunity to take some rust out of my trigonometry. It has also given me the opportunity to do something quite useless but very pleasurable. But I still have to share with you the particular event that triggered this all. I live in Brasilia. Brasilia is a mystic city. Mystic in a very positive sense. Myself, I don't profess any religion, so I feel it very disgusting to see how people keep killing each other all over the world just because one has a slightly different idea about what god is or god is not; or how to dress before god or how to address him some words... In Brasilia we have just about every religion any of you have ever heard about, plus a thousand others none of you have ever heard about. We even have a borough named "Eclectic City" and there is a "Piece University" I'll not make this chronicle much longer than it already is to describe how mystic Brasilia is. I'll not explain how it was first created in a dream by an Italian priest... Suffice it to say that among the religions you can find here, there are those that adore Tutankhamen and worship the sun. One of the demonstration they use to convince people (and themselves) that Brasilia is destined to be the Egypt of the new millenium is the (alleged) fact that on the 21st. of April the sun rises in between the congress towers and shines through an opening in the Kubtchek's memorial shedding light on the Brasilia's founder tomb. Although I've been living here for almos 20 years, I had never taken the trouble of checking this, although I never really believed in it because Brasilia's main axis is inclining about E 20 S. For those of you that do not know that Brasilia looks like are airplane, yes, it does. Seen from above it looks like an airplane or a bird flying in the bearing 110. Since in April the sun is quite to the North, I could not see how it would be possible for it to rise between the congress towers, whose East walls run in the direction N-S +20 and whose North walls run W-E + 20... Yesterday I decided to use Luke Coletti's sundial calculator (http://www.groknet.com/suncalc.html) to find when, around 7 o'clock, we would have an apparent Azimuth of 110 (when the sun would be seen between the congress towers). That's when I found that on October 6, at 7:19 o'clock the sun's Azimuth would be due East. I had an opportunity to check the line I had drawn last Sunday. Than you can imagine my exultation when at the expected time the sun was in the right spot, the shadow was where I expect it to be and the angle between the N-S line I had drawn and the E-W line I was about to draw had 90 degrees. The purest amazement! That's what I wanted to share with you: no scientific breakthrough, no groundbreaking technology, no findings at all, just the innocent elatedness of a 47 years old child! Oh, yes, the sun can be seen between the towers for several minutes a few days before and after the summer (Southern) solstice, never in April 21. But what is reality, what is the meaning of hard facts? Facts can be forgotten or changed to fit any theory, isn't that right? - fernando -- mailto:[EMAIL PROTECTED] http://www.pix.com.br Fernando Cabral Padrao iX Sistemas Abertos [EMAIL PROTECTED] [EMAIL PROTECTED] Fone: +55 61 321-2433 Fax: +55 61 225-3082 19º 37' 57.0" S 45º 17' 13.6" W 15º 45' 04.9" S 47º 49' 58.6" W
