Hi Jim, there is a program called MB-Ruler, which may be what you are looking for. It is also available in an English version. See http://www.markus-bader.de/MB-Ruler/index.htm
Best regards Juergen Hoefeld 2011/11/19 James E. Morrison <[email protected]> > Thanks for all the responses. I should have been more complete in my > request. > > In 1769, The American Philosophical Society sent a team of three men to a > small town on Delaware Bay, south of Philadelphia and near where I live, to > observe the transit of Venus. They determined the coordinates of their > observing site by doing a survey to a point of known latitude some 20 miles > south of their site. The raw field data (bearing and distance) were > published in 1770, as part of the report on the transit observation. I am > attempting to locate the location of their observatory as closely as > possible from the survey data. > > The subject gets complicated in a number of areas; what values did they > use to convert distances to degrees of latitude and longitude, what was the > magnetic compass declination used and was it correct, how should the survey > route be displayed using modern geoid parameters, what precision can be > achieved with an 18th century theodolite with hand divided scales, etc. > > I have written programs that generate kml files to draw the route on a > Google Earth map and it is clear that they used existing roads wherever > possible. It is also clear that some of the 120 data points are wrong, > which could be due to typographic errors when the data was published, > illegible entries in their journal (it was raining the whole time), > inaccuracies in the instrument scales, or many other factors. I am trying > to reconstruct the route actually taken using old maps and to do so with > minimum change to the original data. > > There are 120 points that must be considered and I'm looking for a tool to > use with Google Earth to evaluate a change from the route derived from the > original data to the actual roads (where possible). Almost all of the > roads today were there then, so it is possible to do. > > I've learned a lot about how to draw on a Google Earth map with kml, how > to draw and label connected line segments and how to evaluate the route > using the GPS datum (WGS84). Being as I am, old and fat and lazy and > stupid, I am looking for a tool that takes some of the tedium out of > constructing the real route one point at a time. A protractor that can be > moved around the screen, positioned and rotated would be ideal. I think I > have seen such a tool, but can't find it now. > > I hope this is relevant to the group. > > Best regards, > > Jim > > James E. Morrison > [email protected] > Astrolabe web site at http://astrolabes.org > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > >
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