This is a MapHist list message. News: If you don't get messages anymore, go to http://www.maphist.nl for news about the new MapHist Forum o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o +
 Thank you all so
much for your answer to the mystery of the oddly labeled compass
rose. I figured that it had to be a navigational aid, but never
would have guessed 17.5 leagues had anything to do with it. Those
old mariners were pretty clever!I checked the rules for posting and as long as I keep it under 50K, posting an image is OK. There are two original images (4.5 MB ea), which I'll send to anyone who wants them. Here's a composite (because neither image shows the entire rose) BTW, if anyone recognizes the style, I'd be interested to know from what century this could have been used. It from Columbus' time or is it more recent? Regards, Bill Thoen GISnet - gisnet.com On 12/27/2011 5:08 AM, � wrote: This is a MapHist list message. News: If you don't get messages anymore, go to http://www.maphist.nl for news about the new MapHist Forum o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + o + I think it is an illustration of the 16th century "rule to raise a degree", i.e. a means of calculation of a ship's position based on the assumption that there are 17 1/2 leagues to a degree: If you sail north or south you have to sail 17 1/2 leagues to arrive one degree to the north or south. And so on for every point of the compass (11,25 degrees). And there can only be 8 numbers, because if you sail east or west your latitude doesn' t change at all. Diagrams of this sort can be found in manuals of navigation of the 16th and 17th century. Dr. Wolfgang K�berer Wolfsgangstr. 92 D-60322 Frankfurt am Main Tel: + 49 69 95520851 Fax: + 49 69 558400 e-mail: koebe...@navigationsgeschichte.de |
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