The federal government's budget-cutting efforts are causing annoying ripples, along with swamping waves.

Consider the Library of Congress: Not only will public hours be curtailed starting March 9, but starting this Monday it will be harder to get into and out of some of its buildings. To save on the security guard payroll, the library is permanently closing one of the two doors to its Adams Building (on the Third Street side) and is closing two of the four doors currently in use at its Madison Building, except during the midday lunch period.

Nancy Bush, spokeswoman for the library, said that there are 26 vacancies among 157 authorized positions on its security guard force. As a result of closing some of the doors and curtailing the hours that the library is open to the public, these positions will not be filled, she said.

The monolithic, block-square Madison Building, newest of the library's three-building Capitol Hill complex, was built with five entries. One is near each corner and one is on the library's Independence Avenue front.

Several months ago, the southeast entry, at Second and C streets SE, was closed without warning. Now the entrances on First and Second streets just south of Independence, favorite drop-off and pickup spots for many auto-commuting employes, will be closed except between 11 a.m. and 2 p.m. weekdays. That leaves only the Independence Avenue and the southwest entry, near the Metro station at First and C, as Madison's only full-time entrances during working and visiting hours.

The inconveniences, "in view of the fact that we are having so many severe fiscal problems, is something people will have to accept," said Bush. The situation was discussed with spokesmen for employe unions and they agreed, she said.

As a safety measure, the closed doors will be equipped with electromagnetic devices that will permit their use as exits in case of fire or other emergencies. New Metro Number

The Metro transit authority has a new number for information about bus and subway routes, schedules, fares and related matters. It's 637-7000. I tried it yesterday and, to my surprise, got right through instead of being put on hold. The information service is staffed from 6 a.m. to 11:30 p.m. daily. We Slipped Up

Gordon Hawk, a member of the staff of Sen. Charles McC. Mathias Jr. (R-Md.), said Metro Scene erred yesterday in the dates that Baltimoreans Herbert R. O'Conor (D) and John Marshall Butler (R), served simultaneously in the Senate. The period was from 1951 to 1953; misinterpreted notes are to blame.

Both Hawk and my colleague Tom Edsall noted that, although his political roots are in Baltimore, Sen. Paul S. Sarbanes (D) is from Salisbury, which he has used to political advantage in seeking votes on the Eastern Shore.