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    Re: recommendation for slide rule ?
    From: Gary LaPook
    Date: 2009 May 20, 20:28 -0700

    You don't need to write down any intermediate results if you can
    remember the result of the first part of the calculation, the product
    of sine lat times sin dec, long enough to add it to the results of the
    second part of the calculation, cos lat times cos dec times cos LHA,
    with which to complete calculation of Hc. .
    On May 19, 6:41�am, oystercatcher  wrote:
    > Is it possible using a slide rule to compute say Hc
    > without writing down intermediate results?
    > What would the steps be?
    > With azimuth and the subtraction, I suppose it
    > would be necessary to resort to paper for the
    > final calculation?
    > On Sun, May 17, 2009 at 6:21 PM, � wrote:
    > > I like the K&E 4080 because the trig scales are marked in degrees and
    > > minutes so use the same units as other methods of celnav. The 4081 is
    > > almost identical except the scales are marked in degrees and tenths of
    > > degrees. Take your pick.
    > > PS. they are things of beauty.
    > > gl
    > > On May 16, 10:16�am, corallina  wrote:
    > >> Awhile back some pdf files were posted containing a bygrave
    > >> type computer. �I believe it was the original poster did a
    > >> comparison using his keuffel and esser 4080 slide rule against
    > >> the bygrave and perhaps a calculator.
    > >> Now I am interested in trying a slide rule. �It would seem that
    > >> ebay has the most to offer and I have checked prices for
    > >> the one mentioned above. � At this time I am only interested in
    > >> using the slide rule for sight reduction.
    > >> Being rather ignorant of slide rules I would appreciate if there are
    > >> other models that the list would recommend giving me a few
    > >> more options before purchase.
    > >> Thank you.
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