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Thank you, John. I was wondering about the word "haversine" when I came up 
with a wild solution on my first pass through the formula, because "hav" 
evokes "half". 

Tracking the source of my error I went back to Vol. Ii of my green Bowditch 
and found in the explanation of its table of haversines: "hav A = ver A = 1/2 
(1 – cos A) . . ."  Obviously, I overlooked that 1/2. Tsk, Tsk, Hewitt. Yeah 
well, eventually light breaks where no sun shines.

One of the things I liked about the Martelli is 'only one rule.'  Once in a 
while in the past I'd run into a navigator who used haversines and the ABC 
table but by then I had the sine/cosine formulas for Hc and Z in my DNA and 
never pursued it.

Your remark about the Reed tables opening flat reminded how nice that is. When 
Seven Seas Press took on four of my books  they told me they would be "bound 
flat", which I didn't get at the time, but was delighted when the books came 
to hand. So, I've ordered a 2013 Reed's Astro Nav. from Amazon.

Now that I have reached the age of assessment, I'm happy to be able to explore 
all the interesting things I let pass a long time ago in a galaxy far, far 
away.

Thanks again, John.

Merry Christmas, 

Hewitt


Sent from my iPad

On Dec 24, 2012, at 1:26 AM, "John Brown"  wrote:

> Hewitt wrote:
> 
> Since havt = (1– cost )......
> 
> 
> 1-cos t = versine t (versines are used in place of haversines in Burton's 
4-figure tables - it makes no difference to the results, when substituted in 
the cosine haversine formula)
> 
> hav t(or half versine t) = (1-cos t)/2
> 
> John
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