+TURKISH.+ The Ottoman Turks, who began their conquering career under Osman I. in Bithynia in 1299, had for a century been occupying the fairest portions of the Byzantine empire when, in 1453, they became masters of Constantinople. Hagia Sophia was at once occupied as their chief mosque, and such of the other churches as were spared, were divided between the victors and the vanquished. The conqueror, Mehmet II., at the same time set about the building of a new mosque, entrusting the design to a Byzantine, Christodoulos, whom he directed to reproduce, with some modifications, the design of the “Great Church”--Hagia Sophia. The type thus officially adopted has ever since remained the controlling model of Turkish mosque design, so far, at least, as general plan and constructive principles are concerned. Thus the conquering Turks, educated by a century of study and imitation of Byzantine models in Brusa, Nicomedia, Smyrna, Adrianople, and other cities earlier subjugated, did what the Byzantines had, during nine centuries, failed to do. The noble idea first expressed by Anthemius and Isidorus in the Church of Hagia Sophia had remained undeveloped, unimitated by later architects. It was the Turk who first seized upon its possibilities, and developed therefrom a style of architecture less sumptuous in color and decoration than the sister styles of Persia, Cairo, or India, but of great nobility and dignity, notwithstanding. The low-curved dome with its crown of buttressed windows, the plain spherical pendentives, the great apses at each end, covered by half-domes and penetrated by smaller niches, the four massive piers with their projecting buttress-masses extending across the broad lateral aisles, the narthex and the arcaded atrium in front--all these appear in the great Turkish mosques of Constantinople. In the Conqueror’s mosque, however, two apses with half-domes replace the lateral galleries and clearstory of Hagia Sophia, making a perfectly quadripartite plan, destitute of the emphasis and significance of a plan drawn on one main axis (Fig. 87). The same treatment occurs in the mosque of Ahmed I., the +Ahmediyeh+ (1608; Fig. 88), and the +Yeni Djami+ (“New Mosque”) at the port (1665). In the mosque of +Osman III.+ (1755) the reverse change was effected; the mosque has no great apses, four clearstories filling the four arches under the dome, as also in several of the later and smaller mosques. The greatest and noblest of the Turkish mosques, the +Suleimaniyeh+, built in 1553 by Soliman the Magnificent, returned to the Byzantine combination of two half-domes with two clearstories (Fig. 89). [Illustration: FIG. 87.--MOSQUE OF MEHMET II., CONSTANTINOPLE. PLAN. (The dimensions figured in metres.)]