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Re: Double Altitudes: Prelude to Sumner's line?
From: Jim Thompson
Date: 2005 Feb 28, 17:24 -0400
From: Jim Thompson
Date: 2005 Feb 28, 17:24 -0400
Thanks Fred. Herbert Prinz emailed me offline to suggest that perhaps I had mis-typed "latitude" for "altitude". He is correct: Sumner's original wording was, "Double Altitudes". I did find some google postings about "double altitudes", but I remain unclear about the purpose of that method, and how it might have given Sumner the idea to rework a sight using a second, theoretical latitude, which eventually caused him to realize that such points lay on a line of equal altitudes. So my question now is, what is (was, more correctly), the meaning of "double altitudes"? Jim Thompson jim2@jimthompson.net www.jimthompson.net -------------------- Outgoing email scanned by Norton Antivirus
