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Doc. 203.] 597
REPLY TO SCHENMARK.
But if they institute them for from twenty to thirty pairs of
stars, and for each month in the year, and for three or four
years, and if then application be made to the problem before
us, this method will certainly meet with their approval.
In the "Upsal Acts ” for the years 1723 and 1724 is con
tained a practical observation of the then Professor of Astro
nomy at Lund, which was made in accordance with the
method as it was then stated. His expression in the “ Acts"
is, that the method is practicable, though very difficult. The
difficulty, however, arose from the fact that the practical
rules were not given as in the last publication.
You say something about the time at sea. Experienced
seamen, have an instrument with which they make very exact
observations of the sun, at twelve o’clock noon ; and by these
observations they set their clocks, which may be done every
day when the sun shows itself.
The method itself was published by me in 1721 ; but then
it was not communicated to any Society, nor were any
practical rules given, which depend upon ephemerides; it
could not be used, therefore, by sea-faring men ; for its case
was exactly like the observation of a lunar eclipse, which
was not computed for a certain definite meridian.
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