A wave of false alarms sent Cambridge fire trucks and police cars scurrying around the Square for two hours yesterday afternoon. "Jokers" reported two bogus calls, and a faulty sprinkler system accounted for another.

The first came from the Cambridge School of Design at 61 Kirkland Street at about 3:30 p.m. Five engines and two radio cars went out to find no fire, or even smoke, when at 3:45, another call came. They raced to the Oxford Grill on Church Street to had a surprised manager wondering where the fire was.

Fire officials said they could not trace these two calls, but suspected "Jokers" who were playing on the department's tenseness over the fires that occurred here last week-end.

The third alarm, at 5:15, was caused by a faulty sprinkler system in one of the University Press buildings on University Road near Battle Square. Fire trucks blocked Mt. Auburn Street for almost 15 minutes, while evening traffic piled up as far as the Lampoon building.