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I wonder if anyone has a copy of, or has easy access to, "From sextant
to satellite navigation", by Friedrich Jerchow, which was published in
1987, in English and in German?

The question that I am trying to resolve was asked a long time ago on
the old Nav-l mailing list and still awaits a proper answer. It is
this: "When, and by whom, was the first true micrometer sextant
introduced?"

Jean Randier, in "Marine Navigation Instruments", of which I have the
1980 English edition, shows on page 119 a page from a Plath catalogue.
This illustrates a quintant, a wider version of the sextant, used
particularly by hydrographers, described as "Vermessungsquintant mit
Trommelablesung". This undoubtedly has all the vital characteristics
of a modern micrometer sextant.

Below it on the page is a "Loth-sextant", which appears to show the
standard Vernier (= nonius) instrument of the time. So it appears that
the catalogue is at a transition-date, between the two technologies.

The question at issue is the date of that catalogue. Randier describes
it as "published about 1902", but that is irritatingly indefinite; to
me, that catalogue doesn't look as though it had such an early date.

So that leaves the date of the introduction of the Plath micrometer
quintant still somewhat open. I wonder if the Jerchow book referred to
above, which I think was published by Plath, offers any clues about
that date?

George.

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


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