AFTER nearly 40 years of public service, Mayor Alfred E. Vellucci is calling it quits.

There is much in this grand old man of Cambridge that will be missed. Probably the mayor's best known attribute among Harvard students is his rhetorical fondness for bashing academia. Others may know him for his attacks on condo developers, sanctimonious do-gooders and bureaucrats, or his promotion of worthy causes from world peace to Italian home cooking.

But when Al Vellucci's speeches no longer echo in Sullivan Chamber, the city will still reflect the mayor's more serious achievements: Harvard's voluntary payments to compensate the city for its tax-exempt property; city government attention to the hazardous side of Cambridge's many chemical and biotechnology companies; and above all, Vellucci's contributions to the rent control ordinance and his steadfast support for that law.

As a new generation of yuppies vie to succeed Al Vellucci, their voices sound flatter and harsher than the full declamations Cambridge has come to expect of its last New Deal populist. Like Harvard Square, the City Council is losing its human touch.

We doubt that any of the mayor's would-be successors can replace Vellucci's combined ability to act on his liberal opinions while winning votes from the more traditional neighborhoods. When the next Council takes office a year from now, we may be missing Al Vellucci more than we expect.