A "Nilometer" is a historical device used to measure the water level of the Nile River. It consists of a vertical column with marked gradations, often resembling a long ruler (📏), and is typically placed in the river or on its banks. The purpose of a Nilometer was to monitor the river's water level, which was essential for predicting floods and managing irrigation systems in ancient Egypt. The symbol 🌊 represents the flowing water of the Nile, emphasizing its connection to the description.