Artcle of the month June

Oughtred sundial is older than Oughtred?

Towards the end of 2008, Nicola Severino found a picture of an Oughtred sundial in an old book ¹⁾) in German, titled “Astronomical drawings”.
An Oughtred sundial is made by stereographically projecting the date and hour lines from the celestial sphere onto the horizontal plane.
The figure below shows them as arcs.
There is a scale for the altitude of the sun on a ruler pivoted about the centre.

For more on the Oughtred sundial, see “Article of the month”, 2007, month 02.

A computer-generated pattern is overlaid. It is clear that the patterns match quite well. .

The book in question was written between 1508 and 1520. Oughtred lived from 1574 to 1660.
Therefore, the Oughtred sundial was known before Oughtred’s birth.
Of course, this may be a case of parallel development.