Local authorities apparently feel that Princeton weekends are proper times for rioting--for they let 15 of the 16 students arrested last night go with a pleas of nolo contender and payment of costs.

The sixteenth case, involving the damaging of a Cambridge police car, was field by Chief John R. King of the police force.

The release of the students was apparently arranged by Bernard A. Barr, a New York attorney, who asked to speak privately with the judge before the nine a.m. trial. Barr, in town for the weekend, spoke with Judge Arthur P. Stone for five minutes, following which the judge let all the students go with a payment of $5 costs.