Passage 6.20.12
δὲ ἐπὶ τῷ βωμῷ χαλκοῦς κεῖται τὰ πτερὰ ἐπὶ μήκιστον ἐκτείνων. ἀνακινεῖ μὲν δὴ τὸ ἐν τῷ βωμῷ μηχάνημα ὁ τεταγμένος ἐπὶ τῷ δρόμῳ· ἀνακινηθέντος δὲ ὁ μὲν ἐς τὸ ἄνω πεποίηται πηδᾶν ὁ ἀετός, ὡς τοῖς ἥκουσιν ἐπὶ τὴν θέαν γενέσθαι σύνοπτος, ὁ δελφὶς δὲ ἐς ἔδαφος πίπτει.
On the altar itself stands an eagle of bronze, spreading its wings to their full length. The mechanism within the altar is set in motion by the attendant appointed to manage the race; when activated, the eagle leaps up into the air so that it becomes clearly visible to all the spectators who have come to witness the spectacle, while the dolphin falls down onto the ground.