Re: 16th century navigating/surveying

[Fernando Cabral]

Jim Morrison wrote: The attempt by the Spaniards to find the longitude of Mexico City was done on September 26/27, 1577. Observers in Madrid and Mexico City both observed the end of a total lunar eclipse.  The value they came up with was 94.5 degrees longitude difference between Madrid and Mexico City, versus the true value of 95.46 degrees (+ or - depending on the exact location of the observers).  The one degree difference resulted from attempting to determine the exact time the eclipse ended and the Mexico City team was late by four minutes. This result seems pretty good to me for two guys working with the naked eye and an ephemeris derived from Ptolemaic astronomy. How can you say "pretty good"? This is astoshing, miraculous, impressive! - fernando -- Fernando Cabral                         Padrao iX Sistemas Abertos mailto:[EMAIL PROTECTED]              http://www.pix.com.br Fone Direto: +55 61 329-0206            mailto:[EMAIL PROTECTED] PABX: +55 61 329-0206                   Fax: +55 61 326-3082 15º 45' 04.9" S                         47º 49' 58.6" W 19º 37' 57.0" S                         45º 17' 13.6" W