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Andres:

My Apologies. in my last mail I made an error when I implied the Delambre
and Mechain used  Reflecting Circles for their measurement.
 I was close but not close enough. What they used of course was a Repeating
Circles using the methods I described but the instrument did not have any
mirrors. Their methods would still apply to the Reflecting circle with
little modification.
Their instrument comprised Two telescopes, one on either side of the
calibrated circle and  pointing separately at the two targets. They did not
use the two mirror arrangement invented by Mayer.    
However I still recommend the book. I should have read it again before
sending my last mail.

CLIVE

> -----Original Message-----
> From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf
> Of Andres Ruiz
> Sent: 09 March 2009 10:40
> To: NavList@fer3.com
> Subject: [NavList 7602] Re: Circle of reflection
> 
> 
> 
> 
> Diving in the list I have found some references to the circle:
> - In [NavList 1501] Alex Eremenko write: In Bremerhaven museum I saw some
> very interesting reflecting circles (by Pistor and Martens), equipped with
> detacheable oil lamps on each vernier.
> Alex, have you got any pics to share?
> 
> And Frank Reed said that in Mystic there are some circles.
> Bowditch and Chauvenet Vol.2 have included a description of this
> instrument. Really, they were used in the States?
> 
> 
> 
> [NavList 7580]:
> ---1. It's pleasing to note that the Royal Society is again providing
> copies of its historical papers free of charge. Normally, they are only
> available
> rather expensively, through Jstor. I don't know how long this will last.
> 
> --> George, See http://royalsociety.org/ : "Royal Society Publishing is
> pleased to announce that our online journal content is now hosted on the
> HighWire H2O platform and, to celebrate, all our published content will be
> FREE to access until 31 March 2009."
> 
> ---2. Even for those that may have no technical interest in that paper
> itself,
> it's worth taking a look at the quality of the engravings. ...
> Nevertheless, to my mind they compete with any work-of-art as
> things of beauty. Is that just my odd mind? What do others think?
> 
> --> I am totally agree with George, the engravings are very beautiful,
> something like a 1800�s CAD 3D
> 
> 
> [NavList 7581]:
> Clive, is it possible to hear your comments about your circle?...
> 
> 
> Andr�s Ruiz
> Navigational Algorithms
> http://www.geocities.com/andresruizgonzalez
> 
> > 
> 
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