In Turkey and in Cairo there are some sundials that have common characteristics and that can be classified, as has done prof. Nusret Cam of the Ankara University, as "Ottoman sundials".
(The Ottoman empire was founded in 1299 and had term in 1923) All the most beautiful Islamic sundials that can be seen in our days are Ottomans sundials: from the famous Ibn al Shatir's sundial in the Omayade Mosque in Damascus (1371) to those that are on the walls of Istanbul Mosque. The sundials that have remained, as those in the photos, were all you made in the XVIII and XIX centuries. Since in these centuries the mechanical clocks on the public buildings were already in use also in the East countries, these sundials were not made with the purpose to mark the hours of the day but only show the instants of the prayers, that cannot be read on a common sundial and that today are published on the daily papers . The simplest of these clocks have only a group of almost parallel curved lines, (in vertical quadrants with the concavity downward), that, with a gnomon perpendicular to the wall, give the instants in which given intervals of time remain before the beginning of the main afternoon prayer (Asr). The photo Sundial-yeni camii2 (Cami in Turkish means Mosque) is an example of these kind of sundials. Is the writing on the curve at the top the is word "Asr" (*ﻋﺻﺭ*). Generally the time intervals are not given in minutes but in degrees of hour angle (1 degree = 4 equinoctial minutes) and are of 5° (20min). In the photo there are 10 lines (often they are only 9 are) and the times go from 20min to 3h (from 5° to 45°) before the prayer. In more complex dials we find the lines of the local solar time , often limited inside a frame that surrounds the quadrant. Among these lines there is always the meridian line (noon line), connected to Zuhr prayer. According to one of the customs adopted in the Islamic world the Zuhr prayer must be recites when the disk of the Sun has crossed the meridian line (it is forbidden to begin the prayers exactly in the instants of the noon, of the dawn and of the sunset). Moreover there are cases in which other lines are drawn in the dial as those that show the time that lacks to sunset (prayer Maghrib), to the end of the astronomic evening twilight (prayer Isha') and finally to the beginning of the morning twilight (prayer Fajr). In the dials in which there are the lines of the prayers and also those of the solar time we find always an orthostyle (for the prayers lines) and a polar style that "is held" by the orthostyle . In the photo Sundial-yeni camii1 we find: the lines of the hours (solar time) in the right part of the picture and the writing "Asr" in the center. The prayers lines have disappeared The sundial in the photo Sundial-yeni camii3 has the hours to sunset (italic) numbered from 1 to 7 (*٧*), those of the hours from dawn (babylonic ), the curve of the prayer Asr and the lines of the zodiacal signs. In the little clouds are written the names of the signs: Capricorn, followed by Sagittarius (near to the gnomon) etc. The three sundials were built around of 1669 (1074 H) In the fourth photo there is a very modern sundial: 2002. Best wishes Gianni Ferrari
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