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+--- Thread: IfA Survey and measured recording survey (/showthread.php?tid=4506)
IfA Survey and measured recording survey - Wax - 28th June 2012
Apologies to Red Earth but my previous incarnation makes me twitchy when presented with archaeological surveys. I do recommend trying to understand a little bit about the base mapping for this country that we all supposedly hang our surveys on
[URL="http://www.ordnancesurvey.co.uk/oswebsite/freefun/geofacts[/URL]
Not sure about the free fun though
still havnt go this linking quite right yetThere is a lot in archaeology that I do not know much about or less than I would like but I am happy to put my hand up to that and admit my ignorance.
IfA Survey and measured recording survey - CARTOON REALITY - 28th June 2012
Seeing as we're talking about maps I don't know if any of ye have seen DaVinci's map of Imola (this is not a great link, image too small, please go out and find a larger one.)
http://commons.wikimedia.org/wiki/File:Leonardo_da_Vinci_Map_of_Imola.jpg
1502 (before Mercator was even making filthy nappies), done using basic measuring devices (probably a circumferentor used too - a primitive theodolyte.) It would be good to overlay this on the modern street plan and see how well it matches. Try comparing with some of John Speed's stuff made over 100 years later http://en.wikipedia.org/wiki/File:Dublin_in_1610_-_reprint_of_1896.jpg
Da Vinci was shit hot!!
IfA Survey and measured recording survey - RedEarth - 28th June 2012
Well worth reading, if you haven't already, is 'Map of a Nation' by Rachel Hewitt. Not particularly relevant, but interesting.
IfA Survey and measured recording survey - CARTOON REALITY - 28th June 2012
Quote:The correction I am thinking about is something called the Scale Factor, this is a figure the OS use to apply to their measurements to bring things in to fit the National Grid. This would vary according to your location in the country but it was crucial to apply to your observations to enable you to fit your survey to the National Grid. It was not strictly a correction for curvature of the earth but a correction to fit your local survey to the National Grid. The grid (or projection) being developed to enable coverage of the whole country taking into account the curvature. If you measure between two OS co-ordinates stations over some distance you may notice that the distance measured may not be the distance that Maths would suggest should be between the two points. There are many different types of grid and before the National Grid the county mapping used its own local grids hence mis matches at the edges of county sheets. If you have ever tried to overlay large areas of old mapping over the current you will see these discrepancies quite clearly with some areas appearing slightly elongated when compared to the modern map.
Excellent! And could you please provide a small vignette in plasticine to illustrate the above?
IfA Survey and measured recording survey - Wax - 29th June 2012
CARTOON REALITY Wrote:Excellent! And could you please provide a small vignette in plasticine to illustrate the above?
If you provide the plastacine I will fashion a model at 1:1 ( I may be some time
)