Address:
Cap^t Mathew [sic] Flinders R.N.
    Mary Street
      Fitzroy Square

Annotation:
Nov. 10.1812 M^r Horsburgh

                East India House
                    10^th Nov^r 1812

Sir
    The Editor of the Naval Chronicle has communicated
to me, some Observations made by you, on an extract from
the Introduction of my Directions for Sailing to & from India &c.
which appeared in the N.C. of last month. — The observations
you have made relative to the denomination of the magnetic
from the true meridian, are perfectly correct — I was led into
the error you have noticed by the perusal of some Book which
I had taken a note from, and being busied correcting the {Proofs}
and making an Index to my Book, at the time I was writing
the Introduction, I did not consider the subject in my mind
when I adverted to the Variation, but after the Book was
published I perceived my mistake when it was too late
to correct it. — Had I apprehended the Editor of the Naval
Chronicle intended to have extracted any thing from the
Introduction of the Book, I should certainly have apprised him
of my mistake, which I hope will be of no material consequence,
as few Sailors I fancy will take the trouble to peruse the
Introduction.

    Your paper on the Variation published in the Philosophical
Transactions, much attracted my attention, and having been at
the meeting of the Royal Society when it was read, I was
induced to ask my friend Cap^t Heywood to make some obs^ns
at Spithead, conceiving that to be a convenient place where the