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Re: Nautical astronomy was different
From: Bruce Stark
Date: 2004 Oct 22, 13:14 EDT
From: Bruce Stark
Date: 2004 Oct 22, 13:14 EDT
Jared,
You said: "So what Bowditch said translates into modern Ynglitch as:
'The accuracy of a lunar depends upon the proper maintenance [control,
upkeep, performance monitoring and adjustment] of the chronometer.' "
That's probably as good a guess as we can make from our present perspective. But, in this instance, we don't have to guess. In his next paragraph, Bowditch tell us what he means.
"The best method of regulating a chronometer at sea, is by taking an altitude of the sun when rising or falling quickly, or when bearing nearly east or west, the altitude being sufficiently great to avoid the irregular refraction near the horizon, and noting the time by the chronometer. With this altitude, the latitude of the place, and the sun's declination, find the mean time of the observation by either of the preceding methods: the difference between this time and that shown by the chronometer will show how much it is too fast or slow."
The "preceding methods" he refers to are under the title: "To Find the Time at Sea, and Regulate the Watch, by the Sun's Altitude." They are two ways of working a time sight.
Time sights were called "observations for the time" back then. Apparently the term "sight" hadn't wasn't used until later.
Bruce
You said: "So what Bowditch said translates into modern Ynglitch as:
'The accuracy of a lunar depends upon the proper maintenance [control,
upkeep, performance monitoring and adjustment] of the chronometer.' "
That's probably as good a guess as we can make from our present perspective. But, in this instance, we don't have to guess. In his next paragraph, Bowditch tell us what he means.
"The best method of regulating a chronometer at sea, is by taking an altitude of the sun when rising or falling quickly, or when bearing nearly east or west, the altitude being sufficiently great to avoid the irregular refraction near the horizon, and noting the time by the chronometer. With this altitude, the latitude of the place, and the sun's declination, find the mean time of the observation by either of the preceding methods: the difference between this time and that shown by the chronometer will show how much it is too fast or slow."
The "preceding methods" he refers to are under the title: "To Find the Time at Sea, and Regulate the Watch, by the Sun's Altitude." They are two ways of working a time sight.
Time sights were called "observations for the time" back then. Apparently the term "sight" hadn't wasn't used until later.
Bruce
