3. Probably ‘every exaction’ is meant.

4. I.e. custody of prisoners, to ensure their appearance at trial. (Imprisonment was not in use as a punishment.) ‘The same stratagem’ is presumably the separation of this custodial function from other functions. The example of The Eleven is odd, as in fact they performed a dual duty of custody and of executing certain sentences; but Aristotle probably thought of them as custodians first and foremost.