Diodorus of Alexandria

Diodorus of Alexandria or Diodorus Alexandrinus was a gnomonicist, astronomer and a pupil of Posidonius.
Writings.
He wrote the first discourse on the "principles of the" sundial, known as "Analemma". a commentary on this having later been written by Pappus of Alexandria, that is no longer extant. A small number of sentences having survived the centuries and attributed to him are known; these comment on:the differences (for the purpose of defining) between astronomy and natural science ( ) the word meanings for cosmos and star, the nature of (the things being) stars and ["Galaxias kuklos", (those things which are altogether stars are called today the Milky Way)]. He was known to Eudoros. In his dealings with astronomy he was known to Marinus in his commentary on Euclid's "Data" containing quotes of Diodorus's opinions on the meaning of a term.