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Alex,
Just for the record, I did state what the phrase " the error is negligeable
for practical purposes" meant. That is, less than 20 sec error, by German HO
dictate.
I really believe that if one cares about errors less than one minute, he
should use his sextant frequently, and keep track of the apparent errors.
This is because the sextant and the user are a combination, and there can be
personal errors also involved. One of the best ways to do this is with an Hc
plot for various altitudes, which has been mentioned by me and others
earlier. Instrument error of the arc plus personal error will shift the
curve up or down. Eccentricity of the drum and other miscellaneous errors
will cause data scatter. This assumes backlash has been minimized by proper
operational procedures.
Ken


----- Original Message -----
From: "Alexandre E Eremenko" 
To: 
Sent: Monday, January 30, 2006 3:24 PM
Subject: Re: Sextant certificates


> On Mon, 30 Jan 2006, Jim Hickey wrote:
>
>> Seems certificates represent a sense of formality without real practical
>> use.
>
> I am of the same opinion.
> My SNO-T certificate shows +10" everywhere on the arc, which is nonsense
> by itself. I also spent some euros for the fun of having it
> certified by both Freiberger and Cassens-Plath last summer:-)
>
> In fact, my Russian manual says that a sextant should be certified
> EVERY TWO YEARS. SNO comes with many pages certificate where the first
> page is filled by the manufacturer and the rest are supposed to be filled
> in "special workshops" every two years.
>
>> I find it odd that an instrument maker would use this sort of convention.
>
> Not every manufacturer. Cassens-Plath does not make a usual certificate,
> just a statement that "the error is negligiblei for practical purposes",
> whatever this could exactly mean:-)
>
> Alex.
>
>

   

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