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But Alex,

also on Ebay tonight is Trommelsextant 762148 showing certified 
"corrections" that, throughout, never exceed one-half moa (see yr msg 
below).

The errors in this instrument 762148 were certified expressly to exist 
"wegen Exzentrizit�t" -- on account of eccentricity.

The certificate is dated 1984 by a testing firm located in West Germany 
(with locations in Hamburg and Bremerhaven), and whose work, the 
certificate says, was officially recognized by the (West) German 
Hydrographic Institute. I gather that in 1984, the manufacturer of 
record, Freiberger Pr�zisionsmechanik, was producing sextants not in 
West Germany, but in the then- German Democratic Republic, i.e., 
Communist East Germany.
________________________
I struggle to understand the geometry, how in some instruments very 
recently cited on the List, the error owing to eccentricity can 
accumulate so regularly as the worm travels the limb from O deg to 120 
deg, that when plotted the change resembles a sine wave. If this trouble 
is described in Bill Morris's book, I can't find it.

Is the worm defective? Are the teeth on the limb spaced improperly?
--Jared

On 4/15/2012 9:24 PM, Alexandre E Eremenko wrote:
>
> Here is another Freiberger,
> with Russian certificate (independent testing!)
> showing arc errors up t 1'.
> 
http://www.ebay.com/itm/GERMANY-NAVY-MARINE-SEXTANT-Freiberger-/250927074312?_trksid=p4340.m185&_trkparms=algo%3DSIC.NPJS%26its%3DI%252BC%26itu%3DUA%26otn%3D5%26pmod%3D300690727370%26ps%3D63%26clkid%3D7749488791186474526#ht_500wt_881
>
>
>
>
> Alex.
>
>
>
>
>
>

   

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