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Re: Measuring Dip in the 18th Century
From: Alexandre Eremenko
Date: 2013 Dec 29, 01:46 -0500
From: Alexandre Eremenko
Date: 2013 Dec 29, 01:46 -0500
Brad, Thanks, now it works. He says that the reason for the ~10' error was the fuzzy shadow of the Sun on his backstaff. Few lines later he explains how Thomas Harriot (already mentoned in this discussion) found the way to remedy this... It is the same Harriot who made the dip table that I reproduced few days ago. Which evidently has a much better accuracy than 10'. Alex. > http://www.dehilster.info/index.php?doc=http://www.dehilster.info/instrumenten/davis-quadrant/index.html > On Dec 29, 2013 1:26 AM, "Alexandre Eremenko"> wrote: > >> ------------------------------ >> >> >> Brad, >> >> >http://www.dehilster.info/index.php?>doc=http://www.dehilster.info/instrumenten/davis-quadrant/index.htmlto >> >> Unfortunatey, this reference does not work:-( >> >> Perhaps I did not make my point clear. Let me try again. >> We see a dip table made in XVI century. >> We can easily check it by comparing with modern almanac. >> It does not show 10' errors, does it? >> >> Conclusion: They could measure angles in XVI century with >> about 1' accuracy. >> Now I ask: with what device? I conjecture that this was something >> similar to >> backstaff. >> >> On my opinion, all arguments about GPS and modern >> obsession with many digits >> which >> Frank and you give, are not related to this question. >> >> Alex. >> >> >> >> >> >> >> : http://fer3.com/arc/m2.aspx?i=126014 >> > > > : http://fer3.com/arc/m2.aspx?i=126015 > > > >
