Acts 19:40

For indeed we are in danger to be accused concerning this day's riot

(κα γαρ κινδυνευομεν εγκαλεισθα στασεως περ της σημερον). The text is uncertain. The text of Westcott and Hort means "to be accused of insurrection concerning today's assembly." The peril was real. Κινδυνευομεν, from κινδυνος, danger, peril. Old verb, but in the N.T. only here and Luke 8:23; 1 Corinthians 15:30.There being no cause for it

(μηδενος αιτιου υπαρχοντος). Genitive absolute with αιτιος, common adjective (cf. αιτια, cause) though in N.T. only here and Hebrews 5:9; Luke 23:4; Luke 23:14; Luke 23:22.And as touching it

(περ ου). "Concerning which." But what? No clear antecedent, only the general idea.Give an account of this concourse

(αποδουνα λογον περ της συστροφης ταυτης). Rationem reddere. They will have to explain matters to the proconsul. Συστροφη (from συν, together, στρεφω, to turn) is a late word for a conspiracy (Acts 23:12) and a disorderly riot as here (Polybius). In Acts 28:12 συστρεφω is used of gathering up a bundle of sticks and of men combining in Matthew 17:22. Seneca says that there was nothing on which the Romans looked with such jealousy as a tumultuous meeting.