Attacking what he called "antidemocratic and antiknowledge" budget reductions, Librarian of Congress Daniel J. Boorstin yesterday proposed a 1987 budget that would restore most funding cuts that the library suffered this year.

"It has taken two centuries to build this institution. It can be disintegrated in a decade and destroyed in two decades," Boorstin testified before the House appropriations subcommittee on the legislative branch. He asked for $248.6 million for fiscal 1987, an 18 percent increase.

Boorstin spoke of "a nation in terror and decline," of "an incompletely informed Congress," and he said: "The disaster which I describe [at the library], the shame which will come on this nation if the Congress pursues a policy of disintegrating its library, can be averted only if this committee restores" the budget cuts.

To meet this year's cuts, which total $18.3 million, library officials have slashed the hours that its general reading rooms are open to the public by one third, have begun reducing the 5,200-member staff by 300, and have sharply curtailed expenses for acquisitions, preservation, services for the blind and handicapped, and other activities.

"I share your alarm," said the subcommittee chairman, Rep. Vic Fazio (D-Calif.). "You're playing the role of intellectual Paul Revere this morning."

Fazio said the subcommittee will "try to reach a figure that will allow the library to continue to flourish," but he added that the Gramm-Rudman-Hollings budget reduction act is a "buzz saw," and "I cannot in any way dilute . . . what the reality is in the Congress."

The ranking minority member of the subcommittee, Rep. Jerry Lewis (R-Calif.), said the nation faces "an exploding deficit," and he challenged Boorstin "to help us to look again and again" for ways to save money.

"Frankly, you're on the table [and] we're going to need your help," Lewis said to the scholarly Boorstin, who, wearing a red bow tie, sat listening with knitted brows.

Boorstin responded, "I cannot believe that the Congress of the United States cannot establish priorities." He said defense is a priority and "I don't know why knowledge can't be."

Continuing to press, Lewis said he was recently near San Diego where he saw "holes in the mountains there and people are living there . . . Their not starving to death is a very high priority of mine."

Rep. Lindy Boggs (D-La.) praised Boorstin for his "impassioned plea" and added, "We share your distress because it's our distress." A key function of the library is to serve members of Congress.

In this regard, Fazio said congressional staffers were upset because sometimes no one answered the special "quick reference" phone number at the library's Congressional Research Service. Joseph E. Ross, acting director of CRS, testified he would move some personnel around to solve this problem.

Frank Kurt Cylke, director of the library's services for the blind and physically handicapped, testified that he has not been able to provide magazines for many blind people who have requested them -- another result of the budget cutting.

"We're facing a very serious, severe, detrimental cut . . . We are at rock bottom," he said.

Deputy Librarian of Congress William J. Welsh testified that as of yesterday, the staff had been reduced by 111, most through the reduction-in-force procedure. Associate Librarian Donald C. Curran testified that 70 persons have been riffed, but that "probably 55 or 60" of them will "retain" positions at the library.

Fazio said the riffing process may have an adverse effect on recent minority hires, and he asked for a report on the impact. Library officials said they would provide it.

In other testimony yesterday, Peter G. Sparks, the library's director of preservation, disclosed that a fire and an explosion took place last Friday at Goddard Space Flight Center, where the library's scientists are experimenting on a book preservation process.

A building was damaged, but no books were lost and no one was injured, Sparks testified. But the incident and an earlier fire have cast a shadow over plans to construct a multimillion-dollar preservation facility near Frederick, Md.

This "mass book deacidification facility" would use a new gas process, patented by the Library of Congress, to remove acid from most of the library's 13 million books, which could extend the life of a book from 25 to 600 years.

Sparks testified that bids for the plant construction were to be opened in six weeks, but that this may be delayed as the library's scientists seek to discover what caused the fires and explosion.