There is evidence pointing to the spinning wheel being known in the Islamic world by 1030, and the earliest clear illustration of the spinning wheel is from Baghdad, drawn in 1237.[106] Steel mill: By the 11th century, much of the Islamic world had industrial steel watermills in operation, from Al-Andalus and North Africa to the Middle East and Central Asia.[107] Weight-driven clock: Arabic engineers invented water clocks driven by gears and weights in the 11th century.[108] Optic chiasm: The crossing of nerve fibres, and the impact on vision that this had, was first clearly identified by Persian physician "Esmail Jorjani", who appears to be Zayn al-Din Gorgani (1042–1137).[109] The optic chiasm was earlier theorized by Ibn al-Haytham in the early 11th century.[110] Pinhole camera: Ibn al-Haytham has been credited with the invention of the pinhole camera in the early 11th century.[111] Paper packaging: The earliest recorded use of paper for packaging dates back to 1035, when a Persian traveler visiting markets in Cairo noted that vegetables, spices and hardware were wrapped in paper for the customers after they were sold.[112] Bridge mill: The bridge mill was a unique type of watermill that was built as part of the superstructure of a bridge.