Archimedes

Archimedes (Greek: Ἀρχιμήδης) was an ancient Greek demigod son of Hephaestus. He is credited with the creation of many modern machines and an accurate approximation of pi. He is, in modern times, considered as one of the most well-known and one of the greatest of Hephaestus' children. It is the wish among many of Archimedes' modern-day siblings to find the lost works of Archimedes.

The Mark of Athena
While searching for Nico di Angelo with Frank Zhang and Hazel Levesque, Leo Valdez recovered the lost works of Archimedes. He uses them to destroy the eidolons, possessive spirits working for the Earth Mother, Gaea. He planned to take them to Bunker 9 at Camp Half-Blood, to study them further, With Archimedes' works, Valdez hoped to save Camp Half-Blood from the Roman forces at Camp Jupiter.

Trivia

 * Archimedes seems to be to the children of Hephaestus what Daedalus was to the children of Athena.
 * Archimedes was a real Greek physicist, inventor, engineer, and astronomer who was killed by a Roman soldier against the orders of his superiors.