Josef (also José or Joseph) de Mendoza y Ríos (1761–1816) was a Spanish astronomer and mathematician of the 18th century, famous for his work on navigation.

After this, he proposed the creation of the maritime library, located in Cádiz, which would eventually become the Depósito Hidrográfico of the navy.

He also published several tables using the harversine method (of his invention), to facilitate the calculations of nautical astronomy and navigation.

Mainly oriented to the calculation of the latitude of a ship at sea by means of two heights of the Sun and the time elapsed between them, and to the obtaining of the longitude by the method of lunar distances.

As a curious fact about the method of calculation of that time, while writing the last edition of his famous Lunar Tables, in 1815 (ten months before he died drowned in Brighton), he wrote a letter to general Espinosa y Tello (a good friend of him), where he said verbatim: "...