We studied the lake and its shores,

We studied the lake and its shores, an American engineer has found the remains of ancient dams, breakwaters and other monumental buildings. Back in Cairo, he sat for the examination of the geographical sources as ancient or modern. Soon he stumbled upon the medieval map of Egypt based on the ancient maps of Ptolemy of Alexandria, of which it became apparent that in the era of Al-Fayum Depression, there were not one but two lakes: Karun larger than modern, and more Lake Moeris . 
In April 1883, Uaythaus made at a meeting of the Archaeological Society in Cairo and reported breaking news: he found the answer to the riddle of El Fayuma in the writings of Herodotus (Greek historian and geographer who lived in the fifth century BC). Herodotus wrote that this place was the artificial lake, built in the era of Pharaoh Moerisa. It was so great that the length of his circle (3600 furlong) equaled the length of the coast of Egypt. 
Uaythaus also quotes from the works of other historians of antiquity - Diodor Sicilian, Strabo, Makrobiya, Pliny, - to show that not only the Greeks but the Romans knew that El-Fayum Depression is really a artificial lake. It was a very rich source of fish in Egypt, a chain of villages along its shores was the breadbasket of the country. However, these data could not shed light on the mystery of El Fayuma. If depression is indeed used by the artificial lake, who was the author of this project and how the lake's water level is maintained? 
The first clue Uaythaus found in Herodotus, who reported that the water in the lake came not from an underground source and channel of the River Nile. In June 1883, Uaythaus made at a meeting of the Society of Biblical Archeology in London, and reported on their latest discoveries. He announced that the canal linking the Nile to Lake Moeris partially preserved. This artificial channel between the cavity of El Fayum and the Nile, which the Arabs are still called "the Bahr Yusuf," - "Joseph's bed." 
This speech was followed by a series of lectures and articles in which Uaythaus strongly promoted his theory: namely, the Jewish patriarch Joseph was the man who invented, designed and built this huge irrigation facilities.