OSMANLI MUHENDİSLERİNDEN MEHMED SAİD EFENDİ'NİN DİKEY Di1 VAR SAATLERİ HAKKINDAKİ RİSALESİ

Al ih e beginning of the IHıh eeniury, ıhe Üıtoman Eimpirc witnessed a movemeni of change and Innovation, This transformation was first obtnrd in ihe military field with ihe foundation of ihe Bombardier Corps (Vlufeli Hvmbaratitar Otajjtt in 17 W to irain engineers, The preseni study aims to iniro-duce Mehmel Said Efendi, professor of geometry at ihe Bombardier Corps, and his treatise on Ihe construction and selling of vertical sundials. Son of ihe Mufti of Beyşehir anıl a member of ihe iilenm class. Said Efendi wrote various treatises on geometry, astronomy, time reckoning, geodesy and Earth's shape. Said Efetıdi Mecmuası (Süleyman i ye Librarv, I-sad Efendi Nr3704) comprises a treatise dealing with the determination of Ihe deviation of vertical sundials from ihe cast-wcsi direciion and an appendix on Ihe projections of Sun's orbit. In 1735, Said Efendi heard ahouf the selling1 of the vertical sundial from his colleague Abdullah Efendi el-Muzafferi ebBosnavîh an instructor U ihe Bombardier Corps, and wrote a detailed technical account on the issue in 1737. En ihe Islamic world, (he selling of sundial* on Ihe walls of the mosques were of special imparl a nee since religious duties required precise time keeping. In Ihe construction of sundials, ihe deviation of the meridian plane, perpendicular lo the horizon, has to be determined correctly. Said Elendi, in his treatise presented a meihod lo measure the correct deviation degree from ihe easi-wcst direciion relative to the meridian of the sundial and gave caleulaiions of the orbit projections of the Sun. This sundial differed from Ihe sundials normally used by ihe Ottomans, where Ihe drawing starts from I and ends al 6; Said Efendi s drawing siarts from 6 o'clock in Ihe morning and ends at 12 o'clock as in European clocks. At ihe same time his work gives basic information about ihe construction of sundials and the ways of marking ihem on a w all.