Astronomy
Horoscopes setting out the positions of the planets at the time of an individual's birth are available in Chaldea.
MathematicsA follower of Pythagoras, probably before this time, discovers that some lengths cannot be measured with the same unit used to measure other lengths; for example, the diagonal of a square is incommensurable with its sides.
TransportationCarthaginians begin to build quadriremes, ships with four banks of rowers, for their navy with the intention of invading Syracuse. Diodorus Siculus, however, says that workers hired by Dionysius the Elder of Syracuse [b. Syracuse, c. 430 bce, d. 367 bce] were the "first to think of construction of such ships" in 399 bce. See also 399 bce Transportation.




