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John Kabel writes-


>Speaking of romance . . .
>
>I have been reading the Patrick O'Brian series of books with Capt. John
>Aubrey, RN and Dr. Steven Maturin as the main characters.  The first
>book in the series was "Master and Commander, followed up by "Post
>Captain," etc.
>
>Now, in addition to being a very good read, this series is highly
>acclaimed for its historical accuracy.  O'Brian was not a university
>scholar, but has been widely accepted for his meticulous technical
>detail regarding the sailing of British naval vessels of the Nelson
>era.  The series covers about 1798, and I'm into the 1812 era now.

==========

Well, in matters of maritime fiction, everyone to his own taste. I've tried
reading O'Brian but without much enjoyment. I do not think he comes
anywhere near that master of the genre, C S Forester, in his Hornblower
stories, for attention to detail and sheer believability. Just one man's
view. Little is more enjoyable that settling down with a Hornblower book
and a good atlas.

========

He continues-
>
>Jack Aubrey struggles with his chronometers at one point when his best
>one of the three he averages is smashed in a combat action.  But through
>the whole series he never relies solely on his chronometers, being very
>faithful to his "lunars" and his noon sights.
>
>Now, fiction is not fact, but when it has the force of such meticulous
>and proven technical detail behind it, I would suggest that we might
>accept the fact that lunars did not disappear immediately with the
>advent of the chronometer.
>
============

My comment-

The navigator who relied on one chronometer was in a weak position. This
delicate and expensive assembly of cogs and springs could be easily
deranged by a speck of dust in the wrong place. If that speck brought it to
a stop, at least the navigator knew he was in some trouble. If it caused
the machine to gain or lose, the navigator would deduce a wrong position
without realising it, and was very likely to blunder into danger.

Backing it up with a second chronometer didn't help a lot. If the two
diverged in their time, the navigator would know that he should disbelieve
one, but which one?

That's the reason for carrying three. If one starts to go wrong, at least
there should still be two that agree, so the navigator knows which to
disregard. The same principle of redundancy is used in the flight-deck
instrumentation of a modern aircraft.

Jack Aubrey should have been able to continue using the remaining two
chronometers.

To the master of a small merchant vessel, the cost of acquiring one
chronometer was high enough, but the cost of three could well exceed the
value of his vessel. So lunars remained in frequent use for 100 years after
the introduction of the chronometer.

One of the last exponents of the lunar art was Joshua Slocum, whose
single-handed circumnavigation in Spray ended in 1898. Within 10 years,
lunar distances disappeared from the almanac.

George Huxtable.

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george@huxtable.u-net.com
George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
Tel. 01865 820222 or (int.) +44 1865 820222.
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