|
|
Subject: Re: Celestial observations v. Coast Survey Methods
From: Herbert Prinz (hprinz@XXX.XXX)
Date: Fri Jan 18 2002 - 21:39:57 EST
Thanks for the pointer to this highly interesting web site.
Concerning the use of the telegraph, make no mistake: The determination of longitude
was still based on the exact same old celestial methods, mostly timing transits.
Just the technology of time signals (nowadays we would say: time transfer) has
changed. First there were eclispses, then lunar distances, then the telegraph, then
radio, and finally the GPS.
Herbert Prinz (from 1368950/-4603950/4182550 ECEF) (datum-free!)
Chuck Griffiths wrote:
> I always figured they mostly
> took very accurate celestial observations. If you thought so too, check out the
> history of the US Coast Survey at http://www.lib.noaa.gov/edocs/CONTENTS.htm. It
> will completely amaze you. For instance, the first truly accurate longitude
> reference in the US came using the "American Method" - using the telegraph to
> determine time difference between two points.
|