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• posted on July 15, 2005, 2:27 am

Hope this helps a: 43 7/16 b: 42 13/16 CAD works great for things like this if you need any other help just ask.
Chris Melanson BLH Millwork LTD.

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• posted on July 17, 2005, 2:27 am
Chris Melanson wrote:

This one is used to find radius in just such a manner in traffic accident investigation.
C squared M ___________ + ________
8 * M 2
Where "C" is chord meaning you measure between two points on the curve.
"M" is middle ordinate which is the distance between the middle of the chord and the end which is the same distance in which your two chord points meet. With those two variables, you can determine the radius.
Don
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• posted on July 15, 2005, 6:32 am

It might be useful to know that he first measured the chord of the arc and then the sagitta.
Jeff G
--
Jeff Gorman, West Yorkshire, UK
email : Username is amgron
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• posted on July 15, 2005, 12:20 pm

What in blazes is the sagitta?
I suppose you fellows have never heard of a Smoleys book of tables. :-)
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• posted on July 15, 2005, 1:02 pm
wrote:

Are my messages not getting through? I'd like to know, since there are other problems [replies with no sign of the original message] and I need to speak to my ISP aobut that.
The "saggita" is the vertical distance from the chord center to the arc. There's a reason Latin was used, and it's political as well as a bit snobbish, and a long story. It's just another word.

I'd rather have the formula and a calculator. Much easier to carry around, and easy to use with practice.
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• posted on July 15, 2005, 8:39 pm

I agree, I use a calculator or AutoCad when I need the sagitta (:-) I might even lay it out if the radius is small.
The Smoleys post was made with tongue in cheek. Smoleys are not used much any more.
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• posted on July 16, 2005, 3:28 am

You should be ashamed of yourself. The Smoley family will starve to death because people use cheap \$5 made in China calculators from Wal Mart rather than look up the figures in the book for \$90. It will be a sad day when there are no more Smoley tables.
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• posted on July 16, 2005, 1:31 pm
wrote in message

When I first was introduced to Smoleys (1957), there were only mechanical calculators, Monroe and Marchant comes to mind. They cost hundreds of dollars and of course the big advantage they had was extracting square roots. A slide rule or Smoleys was the state of the art in trig calculations. Initially, I had no use for the segmental tables, but that soon changed. I never heard of a sagitta until yesterday. I suppose an old dog can learn new tricks. Being comfortable with trig, finding a radius is no problem with a \$5 calculator. :-)
I do know a fabrication shop that still uses Smoleys, just like I know woodworkers that use hand tools.
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• posted on July 15, 2005, 12:57 pm
On Fri, 15 Jul 2005 07:32:53 +0100, "Jeff Gorman"

That's what he said.

That's what I said, and is what he said, which was clear enough.
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• posted on July 15, 2005, 4:05 pm
Another even easier mode is do use the three points on the circle to draw a circle using CAD and measure the radius.
Walt Cheever