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Many thanks for this - I'd never really (had to) think about magnetic declination, not being a hiker, other than being aware that in my part of the world, compasses always point a few degrees west of true north. Never though about mag dec as a navigation aid when comparing to true (Pole Star) north. I'm sure the age of satnav has eroded our (Earth-provided) inherent navigation abilities, much as other tech has eroded other abilities, e.g. computers and handwriting. I know many people who aren't even aware that the Sun and a clock make good navigation aids, let alone that the Moon and a clock can be used to do the same at night. It'll be interesting for such people if the power ever goes down. Dr Hillary Shaw School of Business, Management and Marketing Harper Adams University College Newport Shropshire TF10 8NB -----Original Message----- From: Eclipse Maps <[email protected]> To: Discussion group for map history <[email protected]> Sent: Sat, 17 Sep 2011 21:40 Subject: Re: [MapHist] Looking for a map with a specific kind of reliability diagram This is a MapHist list message (when you hit 'reply' you're replying to the whole list) o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + >From the description of your mystery map, the isolines you describe seem to be >lines of equal magnetic declination (for converting compass bearings to >geographic bearings). If your map is used for navigation in a pre-GPS era, >then it's reasonable for such a map to contain these lines. You can easily find magnetic declination maps on the internet. Do your isolines match what's on these maps? I suspect they will. best, Michael Zeiler Sent from my iPad On Sep 16, 2011, at 2:21 PM, [email protected] wrote: This is a MapHist list message (when you hit 'reply' you're replying to the whole list) o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + Some info on this - and also apologies for another query on an earlier topic, anyone help here? First the info. On the 1940s 1:1,000,000 world series map no. N G 41 (Makran), 5th edition, 1944, (1st edn was 1928), covers essentially the border area of Iran/Pakistan, from the Persian Gulf, covers 60 - 66 deg east, 24 - 28 deg N, this map has a "RELATIVE RELIABILITY" inset map, showing most of the map to be derived from a "Reconnaissance Survey 1889 - 1932" ... some small irregular portions to the west are derived from a "Rigorous survey 1918-32". This map is part of the series I queried earlier (none of the others have this "RELATIVE RELIABILITY" inset map), in email in December 2006. Now the new query - having had sight of more of this series, from India to France, they have a strange set of what appear to be concentric lines labelled 12 degrees w, 11, 10 etc through 0 to 3 degrees east - I guess with more maps this series would extend. BUT these lines correspond to no spatial system I can imagine. They certainly aren't long / lat lines, though they 'impersonate' them. Rather the 3 degrees W line goes north-south between Italy and Sicily, swoops round S E I guess across Sudan / Somalia (not seen this) and ends up running East-west across the southern tip of India. The 2 deg east line crosses the eastern tip of Cyprus, running NW to SE, crosses the northern tip of Oman running east-west, then turns to the north east across southern Pakistan. So there's some kind of concentric pattern of these, which I guess would be centred on somewhere in western China, at maybe 10 deg east, and the lines exist at least as far out as one in western France, here running north south, labelled 12 deg west. Furthermore, the line spacing appears to become closer in western Europe (where these lines run N-S), compared to spacing in S Asia, where they run E-W 9and run SW to NE in S E Asia, Thailand etc.. Anyone know how these lines were derived, what they were used for (the maps were, as I was kindly informed by several maphsisters, WW 2 aviators, and from a world series). I can try and scan and send if anyione interested. Once again, many thanks for the replies of January 2007, Dr Hillary Shaw School of Business, Management and Marketing Harper Adams University College Newport Shropshire TF10 8NB -----Original Message----- From: John Day <[email protected]> To: Discussion group for map history <[email protected]> Sent: Fri, 16 Sep 2011 19:13 Subject: RE: [MapHist] Looking for a map with a specific kind of reliability diagram This is a MapHist list message (when you hit 'reply' you're replying to the whole list) o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + Disclaimer: I have nothing useful to add to thisdiscussion. ;-) Now, let me ask a naive question: Isn't there a valuejudgement being place here calling these "reliability"charts? Doesn't that presume that latter measurements are more reliablethan earlier ones? I realize that this is the term that is used, but isn't this moreanalogous to the "References" section of paper? IOW,what were the sources for the data. Sorry for the distraction. This is a MapHist list message (when youhit 'reply' you're replying to the whole list) o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o+ o + Content-Type: multipart/related; boundary="----=_NextPart_000_0120_01CC745E.44C4D580" Content-Language: en-gb Dear Dana, The only examples I come across regularlyappear on British Admiralty charts, but only those published as ofsome time (sorry to be vague) around the last couple of decades of the20th century. An exact date could be got from Guy Hannaford ([email protected]), the UKHO archivist who is extremely helpful. It is possible thisis as a result of an International Hydrographic Organization standard.Here is an example: <image003.jpg> Before that date reliability indicationsas to survey data were loosely noted in the chart colophon, but onlyin terms of the date of the most recent survey and the ship andsurveyors who did it. There was sometimes a reference to previoussurveys where that data was incorporated in the new chart. Otherwiseindications of reliability were given by convention - e.g. for vigias.In addition, for soundings (when individual soundings rather thandepth contours were the norm) a different font was used (usuallyitalic) to indicate soundings from previous charts of doubtfulreliability. Hope that helps. Stephen D Dr Stephen Davies CSSC Maritime Heritage ResearchFellow Hong Kong Maritime Museum g/f Murray House, StanleyPlaza, Stanley, Hong Kong SAR, China Tel: (+852) 2813 2322 Fax: (+852) 2813 8033 www.hkmaritimemuseum.org -------------------------------------------------- HKMM is moving to Central Pier 8 in 2012! çÅç`äCéñîéï®äõíâó2012îNëJâùíÜä¬îÂj·ì! -----Original Message----- From: [email protected] [mailto:[email protected]] OnBehalf Of Dana A. Freiburger Sent: 16 September 2011 01:10 To: Discussion group for map history Subject: [MapHist] Looking for a map with a specific kind ofreliability diagram This is a MapHist list message (when youhit 'reply' you're replying to the whole list) o + o + o + o + o + o +o + o + o + o + o + o + o + o + o + o + o + o + o + _______________________________________________ MapHist: E-mail discussion group on the history of cartography hosted by the Faculty of Geosciences, University of Utrecht. The statements and opinions expressed in this message are those of the author and do not necessarily reflect those of the Universityof Utrecht. The University of Utrecht does not take any responsibilityfor the views of the author. List Information: http://www.maphist.nl Maphist mailing list [email protected] http://mailman.geo.uu.nl/mailman/listinfo/maphist _______________________________________________ MapHist: E-mail discussion group on the history of cartography hosted by the Faculty of Geosciences, University of Utrecht. The statements and opinions expressed in this message are those of the author and do not necessarily reflect those of the University of Utrecht. The University of Utrecht does not take any responsibility for the views of the author. List Information: http://www.maphist.nl Maphist mailing list [email protected] http://mailman.geo.uu.nl/mailman/listinfo/maphist _______________________________________________ MapHist: E-mail discussion group on the history of cartography hosted by the Faculty of Geosciences, University of Utrecht. The statements and opinions expressed in this message are those of the author and do not necessarily reflect those of the University of Utrecht. The University of Utrecht does not take any responsibility for the views of the author. List Information: http://www.maphist.nl Maphist mailing list [email protected] http://mailman.geo.uu.nl/mailman/listinfo/maphist _______________________________________________ MapHist: E-mail discussion group on the history of cartography hosted by the Faculty of Geosciences, University of Utrecht. The statements and opinions expressed in this message are those of the author and do not necessarily reflect those of the University of Utrecht. The University of Utrecht does not take any responsibility for the views of the author. List Information: http://www.maphist.nl Maphist mailing list [email protected] http://mailman.geo.uu.nl/mailman/listinfo/maphist
_______________________________________________ MapHist: E-mail discussion group on the history of cartography hosted by the Faculty of Geosciences, University of Utrecht. The statements and opinions expressed in this message are those of the author and do not necessarily reflect those of the University of Utrecht. The University of Utrecht does not take any responsibility for the views of the author. List Information: http://www.maphist.nl Maphist mailing list [email protected] http://mailman.geo.uu.nl/mailman/listinfo/maphist
