Longitude by Wire by Richard Stachurski : from Professional Surveyor Magazine, November 2003. http://fgg-web.fgg.uni-lj.si/~/mkuhar/pouk/SG/Seminar/Astronomska_navigacija/Astronomska_navigacija_zgodovina/Professional_Surveyor_Magazine-Longitude_By_Wire_The_American_Method-Nov03.pdf
Best, 73, Pat Barthelow AA6EG apol <[email protected]>[email protected] *"The most exciting phrase to hear in Science, the one that heraldsnew discoveries, is not "Eureka, I have found it!" but:* "That's funny..." ----Isaac Asimov On Mon, Nov 13, 2017 at 11:39 AM, Jim Harman <[email protected]> wrote: > On Mon, Nov 13, 2017 at 12:32 PM, Gregory Beat <[email protected]> wrote: > > > As a second’s error in time will be about a nautical mile in US > > latitudes, I wonder if anyone has measured with GPS, how good the > original > > surveys were? > > > > Sent from iPad Air > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > mailman/listinfo/time-nuts > > and follow the instructions there. > > > > I think one nautical mile per second is a bit off: > > 86,400 sec/day > Earth's circumference at lat. 41 is about 16,200 nautical miles, so it's > about 16200/86400 or 0.187 mi/sec > > There is an interesting book "Longitude by Wire" by Richard Stachurski that > describes efforts in the mid 19th century to improve the accuracy of > surveys and determine the precise position of North America relative to > Europe. > > This culminated in the use of pulses on telegraph lines to transfer > observatory time to remote stations. With this technique, very careful > measurements, and mathematical advances they were able reduce the longitude > uncertainty to less than 10 feet. > > -- > > --Jim Harman > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
