He is also credited with inventing a water level, a carpenter's square, and, according to Pliny, a lock and key and the turning lathe.
The ancient historian Herodotus twice refers to Theodorus as "the son of Telecles," a Samian artist.
Herodotus credits Theodorus along with Rhoecus with improving the process of mixing copper and tin to form bronze, as well as being the first to use it in casting.
[2] Carl Sagan, in the episode "The Backbone of Night" from his series Cosmos, states that Theodorus is credited with inventing the level, the ruler, the key, the square, the lathe, and bronze casting.
Theodorus wrote a now lost book on the Third Temple of Hera at Samos, the earliest architectural treatise of which we have the name.