I looked all the pages of the 1809 edition of _Theoria motus corporum coelestium in sectionibus conicis solem ambientium_ https://archive.org/stream/bub_gb_ORUOAAAAQAAJ where Gauss used this notation in pages 80-81. Almost all notations are standard enough to be familiar to any modern (2015) mathematician or physicist, with two exceptions : this "7" symbol and ☊ U+260A ASCENDING NODE (which is still standard in astronomy). The Greek letters in particular have a pretty standard shape, and I don't see why this symbol would be the only geek letter using a fancy cursive shape. Even the Latin letters used standard shapes ( italic, roman, a few capital fraktur).
That said, I did not spot a tau in the text, while most of the Greek alphabet was used. Could "7" be a standard shape for tau in 1809 Hamburg ? However, I still think it is a ⦢ U+29A2 TURNED ANGLE Frédéric Le lun 4 janv. 2016 21:38, Raymond Mercier <[email protected]> a écrit : > On further reflection I can well agree that it is tau. The attached images > from R. Barbour, Greek Literary Hands, show clearly (scan 3) the large > upper case tau in several lines, and in scan 4 in the first and other lines > a hooked version of tau. So I withdraw my suggestion of pi. > Raymond > > *From:* Asmus Freytag (t) <[email protected]> > *Sent:* Monday, January 04, 2016 7:58 PM > *To:* [email protected] > *Subject:* Re: Turned Capital letter L (pointing to the left, with serifs) > > On 1/4/2016 10:41 AM, Michael Everson wrote: > > Certainly it does look more like a very common variant of “tau” than “pi” > > > Variant of uppercase tau? > > A./ >
