Sundial of the month July

Eise Eisinga (1744 - 1828) is known primarily as the builder of the world famous planetarium in Franeker.
It took him seven years (1774 - 1781) to build it, but the planetarium is still fully functioning and entirely worth a visit. The amount of things it shows about the solar system is quite amazing.

However, Eise Eisinga was also concerned with sundials, and in his youth published a book of drawings of some 150 sundials.
One of his realised designs is on display in the planetarium museum, and you see a photo of it here.

It is a simple wooden vertical sundial, declining somewhat toward the west, displaying among other things apparent solar time and the date according to the zodiac calendar.
Also shown, by means of vertical lines, is the azimuth of the sun.
On closer inspection, it appears that these lines are not vertical after all, but rather converge slightly going up.
It may be concluded from this that the wall carrying this dial was not exactly vertical, but inclined a few degrees.
Eise Eisinga correctly considered this in his design.

* "Gnomonica or Sundials, all by Compass and Ruler paced out for the Latitude of Dronrijp [Town], 53 Degrees 13 Minutes North, [in the Year] 1762"

Fer de Vries