NavList:

Frank wrote:

> I'll have to  dig up the reference on this, but it's interesting to
> note that the earliest  references to backlash come from the 18th
> century --long before the micrometer.  Supposedly because of possible

> differences in friction between the index arm and  the arc, early
> quadrant users were told to make small adjustments always in the 
> same direction.

Interesting, and that *seems* to match my own (albeit unscientific)
observations. So I wonder if that's a now-obsolete concept that's just
been handed down over the ages and nobody's bothered to update the
navigation texts? Though I suppose it never really hurts anything
(other than maybe a couple of seconds of "re-rack" time) to continue to
always make the final sextant adjustments in the same direction.

--
GregR


--- FrankReedCT@aol.com wrote:

>
> George, you wrote:
> "Those that are trying to  measure to a small fraction of a minute,
> perhaps for lunars, will be most  conscious of the need to defend
> against minute amounts of  backlash."
>
> For what it's worth, even for lunars, I've never seen any  measurable
>
> backlash in any sextant of reasonable quality.
>
> I'll have to  dig up the reference on this, but it's interesting to
> note that
> the earliest  references to backlash come from the 18th century
> --long before
> the micrometer.  Supposedly because of possible differences in
> friction
> between the index arm and  the arc, early quadrant users were told to
> make small
> adjustments always in the  same direction.
>
> -FER
> 42.0N 87.7W, or 41.4N  72.1W.
> www.HistoricalAtlas.com/lunars 
>
>
> >
>


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