§12.1Διὰ τί πορρωτέρω τὰ βέλη φέρεται ἀπὸ τῆς σφενδόνης ἢ ἀπὸ τῆς χειρός;
Why are missiles carried further from a sling than from the hand?
Καἰτοῖ κρατεῖ γε ὁ βάλλων τῇ χειρὶ μᾶλλον ἢ ἀπαρτήσας τὸ βάρος.
And yet, the thrower controls the object with his hand more than when he suspends the weight.
Καὶ ἔτι οὕτω μὲν δύο βάρη κινεῖ, τό τε τῆς σφενδόνης καὶ τὸ βέλος, ἐκείνως δὲ τὸ βέλος μόνον.
And furthermore, in this way he moves two weights—the sling and the missile—whereas in that way he moves only the missile.
§12.2Πότερον ὅτι ἐν μὲν τῇ σφενδόνῃ κινούμενον τὸ βέλος ῥίπτει ὁ βάλλων (περιαγαγὼν γὰρ κύκλῳ πολλάκις ἀφίησιν), ἐκ δὲ τῆς χειρὸς ἀπὸ τῆς ἠρεμίας ἡ ἀρχή·
Is it because, on the one hand, in the case of the sling, the thrower releases the missile while it is already in motion (for he lets it go after swinging it round many times in a circle), whereas, on the other hand, from the hand the beginning is from rest?
πάντα δὲ εὐκινητότερα κινούμενα ἢ ἠρεμοῦντα.
And all things are easier to move when they are already in motion than when they are at rest.
§12.3Ἣ διά τε τοῦτο, καὶ διότι ἐν μὲν τῷ σφενδονᾶν ἡ μὲν χεὶρ γίνεται κέντρον, ἡ δὲ σφενδόνη ἡ ἐκ τοῦ κέντρου·
Or is it both for this reason, and because in slinging the hand becomes the center and the sling becomes the radius (the line from the center)?
ὅσῳ ἂν ᾖ μείζων ἡ ἀπὸ τοῦ κέντρου, κινεῖται θᾶττον.
The greater the line from the center, the faster it moves.
Ἡ δὲ ἀπὸ τῆς χειρὸς βολὴ πρὸς τὴν σφενδόνην βραχεῖα ἐστίν.
But a throw from the hand is short compared to the sling.