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Look at article 1903 in Bowditch, available here:

http://www.nga.mil/MSISiteContent/StaticFiles/NAV_PUBS/APN/Chapt-19.pdf

"v, the difference between the actual change in GHA in one hour and a
constant value used in the interpolation tables; and d, the change in
declination in one hour."

gl

On Jun 19, 10:41 pm, glap...@pacbell.net wrote:
> Here are excerpts from the 1937 N.A The first page shows the time of
> transit of the moon of the Greenwich meridian and contains a "Var. per
> hour" column, variation?, the change in declination inone hour."
>
> http://www.geocities.com/fredienoonan/almanac-1937-136.JPG
>
> The second page contains moon data showing GHA and DEC and has
> separate increments tables for each day based on the the dec change
> and GHA change rates for that particular day. no "v" or "d" correction
> factors are shown.
>
> http://www.geocities.com/fredienoonan/almanac.html
>
> This third link takes you to a site I put up with with excerpts of
> various navigation texts.
>
> http://www.geocities.com/fredienoonan/
>
> gl
>
> On Jun 19, 9:00 pm, frankr...@HistoricalAtlas.net wrote:
>
> > Greg, you asked:
> > "And maybe that's going to be about as good an answer as we can hope for
> > at this point in time - does anyone know when "d" and "v" terms first
> > showed up in the NA as such? There might be more elaboration about what
> > the abbreviations stood for when they were first introduced."
>
> > Yes, that's basically what I was providing you in the previous message. The
> > labels "v" and "d" first appear in the "Abridged Nautical Almanac" in 1952.
> > This is the earliest date when the official British almanac included GHA.
> > This had been introduced 18 years earlier in the American Nautical Almanac,
> > and it was also widely used in the various air almanacs. As I said, the
> > concept of the interpolation constant at the foot of each column on the
> > almanac page was already present in the American almanac where it was called
> > a "code". I also checked a couple of commercial British almanacs from this
> > period (the commercial British almanacs adopted GHA well before the official
> > British almanac). They use a similar principle but again not labeled v and
> > d. So my best guess right now is that the first use of these specific labels
> > for the interpolation data is the British "Abridged Nautical Almanac" in
> > 1952. Here's the full text from the explanation in the AbNA for 1953:
> >  "Interpolation between the tabulated hourly values is provided for by
> > comprehensive interpolation tables, printed on coloured pages at the end of
> > the book, giving for every minute and every second the increments of G.H.A.
> > corresponding to the mean rate of increase for the Sun (15� precisely), the
> > constant rate for Aries (15� 02'.46) and the minimum rate for the Moon (14�
> > 19'.0). The variations from the means are so small for the Sun that they
> > have been deliberately ignored; the tabulated hourly values of the Sun's
> > G.H.A. have been adjusted so that the error thus caused is a minimum. These
> > variations cannot be ignored for the planets or for the Moon, and
> > corrections have to be made for the excess (v) in hourly motion over that
> > adopted in the main interpolation tables."
>
> > So there's an answer: v stands for "excess". :-)
>
> > In the next paragraph:
> > "The corrections for these VARIATIONS [...] are taken directly from the
> > interpolation tables with argument v" and "A similar procedure is used to
> > interpolate the declinations of the Sun, Moon and planets; here d, the
> > hourly DIFFERENCE, is given without sign on the daily pages" (I have
> > capitalized those two words for emphasis). So if you must assign a meaning
> > to v and d, I think the best bets are "variation" (of the rate of change of
> > GHA from the selected mean rate) and "difference," but the catch is that the
> > person who wrote this explanatory section may very well have invented those
> > origins on the spot.
>
> > By 1958, when the modern Nautical Almanac was formed by the merger of the
> > American Nautical Almanac and the Abridged Nautical Almanac (they kept their
> > separate names until 1960), the explanation simply refers to v and d values
> > with no hint of any etymology. Same in Bowditch of the same era. I think
> > this is intentional. The labels v and d really are not intended to "stand
> > for" anything.
>
> >  -FER
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