Joseph Bonomi the Younger into debt and was eventually happy to accept a modestly paid commission to accompany Robert Hay on an expedition, via Malta, to Egypt in 1824. This began a lifelong interest in Egyptology. From 1824 to 1826, he was a member of Hay's expedition where he sketched many antiquities. At Abu Simbel in 1825, Bonomi – responding to Hay's demands for great accuracy – devised a drawing frame (a viewfinder-type device equipped with a sight and a string or wire grid) to help them draw the temples' interior decorations. The expedition then moved on to Kalabsha, where Bonomi laboured to produce
Romanian air tours over Africa Philae Island, and hedgehopped over the temples of Ramesses II and Nefertari at Abu Simbel. They entered Sudan and stopped at the customs point of Wadi Halfa. They flew over the second cataract, then cut the meander of the Nile through the desert, along the Wadi Halfa– Abu Hamad railway line up to Railway Station No. 6, where they overnighted. The following day they flew over the fifth cataract, Atbara, and after the sixth cataract they reached Khartum, where they stayed for two days as the engine of Pantazi's aircraft needed overhauling. After a short stage to Kosti, they reached