Hi Brent, Click on this link http://www3.telus.net/public/rtbailey/images/Birthday%20Lines.jpg to see a sundial with birthday lines. This sundial in Vienna Austria, was designed by Karl Swartzinger for his friend Franz. The lines mark the path of the sun on the birthdays of the all the family members. Note the shadow of the gnomon tip. This indicated I met with Karl and Franz just before dinner, very close to the summer solstice. There are many sundial houses in Austria. This picture is one of many in my presentation "Timelines" available here. Click this link Timelines" to download the 5 MB presentation.
Regards, Roger Bailey Walking Shadow Designs ------------------------------------------------- From: "Brent" <[email protected]> Sent: Wednesday, March 30, 2011 9:45 AM To: "Roger Bailey" <[email protected]> Cc: "Sundial List" <[email protected]> Subject: Re: Sundial house > Hi Roger; > > So if I were to mark the daily hyperbolas on the wall and > then added horizontal hour lines I would have a sundial > inside my house? That would be cool. I could also make one > for the afternoons on the west side. > > I guess we all have a birthday hyperbola. If each birthday > photo had the declination line directly under it, the > birthday window would work all day, not just at sunrise. > Just follow the line the sun is shining on to see whose > birthday it is. > > So this would be a birthday sundial. > The fun part it's inside my house and it is quite large. > > So how would I go about drawing the declination lines? > I have drafting software and an oversize printer. > Maybe I could print something out to actual scale and use > it for a stencil? Or just hang the paper on the wall to see > if it works correctly first might be a good idea. > > I'm not very good at math but I am an expert at copy and paste. > > thanks; > brent > > > > > On 3/30/2011 8:57 AM, Roger Bailey wrote: >> Hi Brent, >> >> The line from the sun spot projected on the wall is >> generally a curved line, a hyperbola, called a declination >> or date line. On the equinox, when the declination of the >> sun is zero, the line is straight. The curvature increases >> day by day with solar declination to a maximum value on the >> solstices. Declination lines are standard features on >> sundials, easily calculated point by point with geometry and >> trigonometry. >> >> Regards, Roger Bailey >> >> -------------------------------------------------- >> From: "Brent" <[email protected]> >> Sent: Wednesday, March 30, 2011 8:03 AM >> To: "R Wall" <[email protected]> >> Cc: "Sundial List" <[email protected]> >> Subject: Re: Sundial house >> >>> Well I made a test birthday window. >>> I cut a piece of plywood the size of one window in an east >>> facing wall. I drilled a hole in the top about 2" diameter. >>> >>> At sunrise it shines a bright sun circle on my wall that is >>> about 12 feet away. The sun spot is about 4" diameter. >>> The edges are crisp and clear. >>> I was surprised at how bright it is even in the well lit >>> room. >>> I was also surprised that it didn't move straight down as >>> the morning progressed but is moving at an angle. I am >>> guessing that it is my latitude or co-latitude angle. >>> Tomorrow I will try and get some accurate marks on it and >>> measure the angle. I'm curious to see if that angle will >>> change during the year. >>> >>> I can see that if I want the spot to shine on a photo at >>> about eye level, the hole in the window needs to be at the >>> correct height, which would be in line between the hanging >>> photo and the east horizon. Obstructions need to be taken >>> into account. >>> >>> brent >>>
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