The Daniel Websters are gone, but the Senate still raises up orators.

Big John Culver (D-Iowa), raging back and forth on the floor like a maddened bear, can speak convincingly for hours without notes against the B-1 bomber or the purchase of what he considers an unnecessary building.

Hubert H. Humphrey (D-Minn.), in high spirits needling opponents on disarmament, twitting his colleagues like a kindly schoolmaster, makes everyone laugh and feel good.

John Stennis (D-Miss.), with his great dignity and sincerity, reminds everyone of the real meaning of the words "gentleman" and "patriot."

The trouble is, nobody's listening.

These performances sound wonderful to the tourists and reporters in the galleries. They read beautifully in the Congressional Record. But they are usually delivered with only a handful of senators present. They seldom affect any votes when the roll is called.

Theoretically, the Senate requires a quorum (a majority of its membership) to be present before doing any business. But, in practice, a quorum is always "presumed" to be present unless a senator demands an actual count be taken. The presumption that a quorum is present allows the Senate to stay in session and even sometimes pass resolutions and bills with only a handful of senators present.

Recently Sen. Carl Curtis (R-Neb.), disgustedly looking around during an important debate in which only 15 or 20 senators were present most of the time, offered a floor proposal that would have required that, regardless of the presumption of a quorum, no business would be enacted unless 25 senators were on the floor. If at any time the presiding officer, by visual count, determined that less than 25 were there, he would immediately suspend operations.

"At the present time, very important matters are presented and there are only one, two or five or six senators present," Curtis said. "What happens? We are busy in committee or otherwise officially tied up. We rush in here and ask some one individual, other than a senator, what it is all about and how to vote. This is not a kid's debating society. This is one of the highest legislative bodies in the world."

Curtis' amendment was brushed aside, in part because it was too big an issue to decide on a floor amendment, in part because many senators just couldn't conceive of senators being able to operate in committee and elsewhere if they had to spend a lot of time on the floor. But his complaint had considerable validity.

When the time comes now for the vote on the debated issue, legislative assistants gather outside the Senate chamber. When a senator arrives, responding to the single loud bell piped through the Senate building that signals a roll-call, his legislative assistant in a quick, whispered conversation tells him what the vote is about and recommends how he should vote. The senator then walks in and yells "aye" or "no."

Sometimes the legislative aide misses the contact, and the senator walks into the chamber without any knowledge of what's being voted on.He gets a quick fill-in from another senator or from the party secretaries, J. S. Kimmitt for the majority, William Hildenbrand for the minority. Then he votes, without hearing a word of the debate.

The recent debate on the ethics code for senators was a typical scene. There were 25 sentors present -- the most at one time in weeks, except during a roll-call. But the senator in the presiding officer's chair was doing a crossword puzzle, at least six others were engaged in animated private conversations, ignoring the debate, and three were busily writing and signing letters.

The four-day debate on the nomination of Paul Warnke as President Carter's arms control negotiator was a good example of great speeches delivered to an empty chamber.

At virtually no time were more than six to a dozen of the 100 senators on the floor.

The reason for this is simply that senators are too thinly spread to spend much time on the floor. They have multiple committee assignments. They have speaking engagements. They must meet with constituents in their offices. They travel home for quick speeches or meetings. They meet with lobbyists. They go to White House or departmental briefings.

Instead of making up their minds from listening to debate, they depend on committee reports, briefings by aides, private discussions to clarity the issues.

In some ways it's a great loss, because the give-and-take of debate, the probing of a legislative argument by a hostile opponent, can often puncture an argument or put it in a different light.

The most recent truly great debates in which there was really widespread participation, with several dozen senators on the floor at most times, go back to the disputes over the federal election laws, 1972 arms limit agreement and the end-the-war amendments of the early 1970s. Big tax bills are perhaps the main exception: everyone wants to get his amendment in.

Few observers believe the trend can be reversed. The only solution, in the opinion of many, is to cut down on assignments to committees (a move was made in this direction with committee reorganization early this year), block committees from meeting in the afternoon (often tried but never really successful), or just to accept the situation and find a way around it.

One move in this direction has already started. Majority Leader Robert C. Byrd (D-W. Va.) and Vice President Mondale have had special closed-circuit TV receivers installed in their offices so they can listen to debate while they work. Thinking in larger terms, Byrd has also proposed a closed-circuit TV system that would pipe the debate into all the members' and committees' offices.

His plan is posing in the Rules Committee, which has a number of other urgent issues it must take up first. But there is a feeling that eventually the closed-circuit idea will go through -- a better-than-nothing compromise that acknowledges the impossibility of keeping senators in the chamber.

The House has already taken a major step in that direction. On March 15, at the order of Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), a closed circuit TV system was set up to beam floor debate to House offices in the Capitol and in the Rayburn Building. After a 90-day trial, it will be decided whether to install it in the other two House office buildings.

"It works great," said one staffer. "You just flick it on and you can follow the whole thing while doing something else."