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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
7 ways to determine longitude
From: Dan Allen
Date: 2003 Dec 24, 07:31 -0800
From: Dan Allen
Date: 2003 Dec 24, 07:31 -0800
I have just started to read an old book called "Spherical and Nautical Astronomy", a two volume set by William Chauvenet who was a professor at Washington University in St. Louis. My copy was printed in 1903 but it appears that it is just a reprint of an 1863 edition. Chapter 7 is "Finding Longitude by Astronomical Observation" where it lists seven different methods, which are: "1st method - by portable chronometers 2nd method - by signals 3rd method - by the electric telegraph 4th method - by moon culminations 5th method - by azimuths of the moon, or transits of the moon and a star over the same vertical circle 6th method - by altitudes of the moon 7th method - by lunar distances" By chronometers it means chronometric expeditions: taking a chronometer from Greenwich to Boston and comparing mean noon times. By signals it includes eclipses, occultations of Jupiter's moons, and terrestrial signals. Interesting. Dan