Typology of Skylights in the Architecture of Mosques’ Domes (A Comparative Study on the Shabāks in the Dome-Houses of Timurid Yazd and Safavid Isfahan Mosques)

The evolution of skylights and the way light is transmitted to dome-houses has always been a chief concern in architects’ mind. In terms of development and technique, such an element has been neglected, however being of significance. This main part, which has a great artistic role in Islamic architecture ​​from the perspective of technique, form and position, has changed over time and improperly replaced with new patterns. The present research is to answer the following question: How was lighting in the dome-house spaces provided through shabāk (jali or skylight) with regard to the promotion of dome-houses construction techniques in the Timurid and Safavid periods in terms of form, design and execution? This research is qualitative and the method of collecting information is based on field and library studies. For this purpose, mosques of the Timurid and Safavid periods in two cities were classified and then, by carrying out a field study, the mosques that had shabāk were examined and finally, three mosques in Timurid Yazd and two in Safavid Isfahan were selected. Here, the samples whose authenticity was not confirmed by valid historical documents nor were they approved by experienced masters were omitted. Findings show that in comparing the architecture of domes from the Timurid to the Safavid period, the position of skylights has been transferred to the lower quarter of the dome (pākār section). In this section, due to the increase in the thickness of dome shells, it was possible to create more skylights. Furthermore, the size of the shabāk mosaic frames has increased and the former simple, rectangular forms in the Timurid era have been transformed into an ogival form, but the elegance of the designs in comparison to the Timurid mosaic shabāks has reduced. Here, as the shabāk mosaics have more consolidation, larger and double mosaics have been used. Adding hamil tiles to the margins of skylights has made them more visible from a distance and an instant recognition of the main surface and shabāk has been allowed. The combination of colors is an important matter in adjusting the amount of light in the Timurid period and due to technical advances in glaze making during the Safavid era, greenish-blue was added to the color combinations on the shabāks. In the mosaic shabāks of Yazd mosques, geometric patterns are predominant forms and they are independent of the dome decorations with fairly simple designs. In the mosaic shabāks of Isfahan mosques, arabesque and khatāi motifs are repeated in the half, and mirror-like in the whole. They are symmetrically placed in a frame.