A letter bomb scare in the Aiken Computer Laboratories caused the evacuation of Piece Hall yesterday morning.

The bomb scare, prompted by a package delivered to Watson Professor of Computer Science Michael O. Rabin at 10:50 a.m., was false alarm, Harvard Police Chief Paul E. Johnson said yesterday.

The package turned out to contain a "harmless book," Johnson said.

Minutes after Rabin's assistant received the package, Boston and Cambridge bomb squads and Harvard police arrived at Pierce Hall and evacuated the building.

Take Five

"The building was evacuated for less than an hour, so most everyone took a short lunch break," said Albert Gold, associate dean for administration in the department of applied sciences.

But Gold said he was concerned about the suspicious package because there has been a history of letter bombs being sent to science faculty members, including a recent incident involving a Yale University professor.

"We cannot be too cautious," Gold said. "There's been more than a decade of serial letter bombings in the computer field and advisories have been posted everywhere. This matched the descriptions of a letter bomb perfectly and we weren't taking any chances."

Rabin's assistant Carol Harlow, who cited the recent history of letter bomb scares, said the package immediately looked suspicious.

"The envelope was peculiar--it had no return address and the label was handwritten; it was metered from New York's Kennedy Airport, and did not look professional," said Harlow.

Since Rabin is on leave in Israel, Harlow brought the package to Gold who immediately notified Harvard police.

"We had a slight scare, but fortunately, the outcome proved not to be too exciting," said Gold.