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We can put the matter of watches in context by comparing the
situation of the geographers who were mapping out the Canadian West
at the same time as Lewis and Clark made their journey to the
Pacific. David Thompson had two watches that were purchased for 12
guineas each in 1794 (perhaps 15 pounds?). These were definitely not
in the chronometer league as they rarely ran better than +/- 5
minutes per day. I think it likely that they had second hands as his
journal entries contain seconds that are not multiples of 5 or 10,
and working by candlelight in the Canadian winter would surely make
estimating to the nearest second an impossible task. We may also note
that despite the poor performance of these watches, they were
obviously adequate for navigation in the hands of one who was skilled
in the art.

George mentioned that we shouldn't take the ease with which we read
off a second hand for granted when considering the difficulties
encountered by these explorers. Although it seems likely that Lewis,
as presidential secretary, would have owned a pocket watch and been
reasonable adept at reading it, he may have recruited an assistant to
observe the watch when making observations to improve accuracy. I
presume this is what George is suggesting may be the reason for the
frequent one minute errors. This explanation does seem to be quite
compelling. I wonder if the errors persist when the expedition was in
the neighborhood of the big bend of the Missouri, at the Mandan
Villages, since they had an accurate map of that region.

   \----------------------------+---------------------------------+
o_,
 O_/ \    Ken Muldrew, PhD      | Voice: (403) 220-5976           |
<\__/7
 <\__  \  Dept. of Cell Biology | Fax:   (403) 270-0617           |
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  "\ L  | University of Calgary | kmuldrew@acs.ucalgary.ca        |
/ /
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/
               Morning coffee recapitulate phylogeny               L/

   

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