Octagonal sundial

Specifications.

Single copy. Brass, patina. The diameter of the circle with the octagon inside it is 284 mm. The thickness of the disc is 5 mm. The thickness of the gnomon is 9.4 mm.

Price 60 000 R.

The sundial measures the mean (civil) time of the fourth zone on the base of true solar time at the meridian of Moscow. The instrument is provided with a detailed graph of equation of time. According to the graph, to get the mean time you are to add the equation of time to the true solar time, depending on the day of observation. In the southern part of the dial, a nomogram is etched that allows determining the time of sunrise and sunset, depending on the calendar date and the value of the declination of the sun (the height of the sun above the ecliptic).