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I had it on my watch list... Too rich for me!

Thomas A. Sult, MD
Sent from iPhone

On Aug 17, 2009, at 4:43 PM, Gary LaPook  wrote:

>
> The MHR1 just sold for 1990 pounds, $3300 US, way out of my price
> range.
> I am glad that I got to hold three of them in my hands last month in
> London.
>
> gl
>
> Brad Morris wrote:
>> http://cgi.ebay.com/U-Boat-MHR-1-Dennert-Pape-Sextant-Calculator-Slide-Rule_W0QQitemZ140338425807
>>
>> currently on eBay.  Looks like a very nice one.
>>
>> For all the talk of the Flat Bygrave (hat's off Gary), there is
>> nothing, absolutely nothing like the feel of this solidly made, top
>> rank instrument.  I recommend it highly!
>>
>> Best Regards
>> Brad
>>
>>
>> ________________________________________
>> From: NavList@fer3.com [NavList@fer3.com] On Behalf
>> Of glapook@PACBELL.NET [glapook@PACBELL.NET]
>> Sent: Wednesday, August 05, 2009 11:19 PM
>> To: NavList@fer3.com
>> Subject: [NavList 9378] Manufacture of Bygraves
>>
>> I was in London last month and made arrangements (with the
>> assistance of Geoffrey Kolbe, thanks again) to see the examples of
>> Bygraves and the HR series held by the Science Museum and by The
>> National Maritime Museum. I attach two photos showing my hot little
>> hand holding examples of each.
>>
>> The Bygrave I saw was a Mk II serial number 105, the same one shown
>> in Van Riet's paper. I measured the diameters of the scales,
>> actually their circumfrances using a tape measure, and my numbers
>> are very slightly different than his. I believe my measurements are
>> accurate to one-half of a millimeter.
>>
>> The circumfrances were:
>>
>> Cotan   174mm
>> Cos     187mm
>> Cursor tube 203mm
>> Knob at bottom of cosine scale  207mm
>>
>> Dividing by Pi gives diameters of:
>>
>> Cotan 55.4mm
>> Cos   59.5mm
>> cursor 64.6mm
>> Knob 65.9mm
>>
>> I am attaching two photos showing two details of the construction.
>> One is a photo of the cotan scale showing that it was printed on
>> paper and then wrapped around the tube. You can see the gap that
>> has developed over time. The second shows a detail of the long
>> pointer, it is bent downward to be near the cotan scale to
>> eliminate parallax.
>>
>> The National maritime Museum has three examples of the HR1 and one
>> example of the larger HR2. The three HR1s were in cans and the HR2
>> had a cover and was obviously meant to be mounted on a desk. The
>> first two HR1s I examined were in perfect shape but the third one
>> (the one I am holding in the picture) was in poor shape. I am
>> attaching two photos of the HR2 one showing the scale revealing the
>> same construction method used in  the Bygrave, a paper scale glued
>> around a tube.
>>
>> It was a thrill for me to actually see these instruments. My first
>> impression was that they are very big compared to the one I
>> constructed which is only one and a half inches in diameter.
>>
>> gl
>>
>>
>> 
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>>
>>
>>
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>>>
>>
>>
>
>
> >

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