2nd century BC Ctesibius and various other Greeks of Alexandria of the period developed and put to practical use various air and water pumps which served a variety of purposes,[37] such as a water organ and, by the 1st century AD, Heron's fountain. Sakia gear 2nd century BC First appeared in 2nd-BC Hellenistic Egypt, where pictorial evidence already showed it fully developed[38] Surveying tools c. 2nd century BC Various records relating to mentions of surveying tools have been discovered, mostly in Alexandrian sources, these greatly helped the development of the precision of Roman aqueducts.