It might have been just another day of madcap pirouettes around the Almighty Dollar, but the Senate, in its ineffable way, managed to make it memorable.

First, the budget Committee met yesterday's deadline for finding ways to trim spending and balance the fiscal 1981 budget. So far, so good.

Then the Democrats, in a group frenzy, stampeded the television cameras to outdo Republicans with tax-cut proposals for next year.

So much for balanced budgets. If that stampede reaches the Senate chamber, the Budget Committee probably can fold its precarious balancing act. c

But the best came last, on the floor. For 90 minutes, they haggled and caterwauled, not over passage of a $15.8 billion supplemental appropriation bill, but over whether they would even talk about the bill.

Majority Leader Robert C. Byrd (D-W.Va.) was doing his darnedest to get the bill moving, since it contains the money to keep Uncle Sam Afloat for the rest of this fiscal year.

So Byrd scheduled the debate for 7 p.m. At that point, Sen. John Heinz (R.Pa.) poppped up to object to consideration of the measure.

Heinz argued that, under the three-day rule, the bill was not eligible for consideration for several hours.

Okay, Byrd said, if Heinz wanted to play by the rules, fine. He would wait until midnight, when the rule would expire, and the members could stick around and debate the bill then.

And, Byrd added, if the supplemental is stalled much longer, there will be no July 4 recess. He would guarantee that by not calling up the usual adjournment resolution.

Back and forth they argued. A quorum call dragged on, to give the hagglers time to work out a deal.At 8:20, Byrd gave up. He renewed his request for a waiver of the three-day rule. He said one man (Heinz) was "impinging on the convenience of 99 others."

More huddling, more haggling on the floor. At 8:29, Heinz removed his objection and freed the Senate to proceed with the supplemental appropriation. oHe then promptly departed for friendlier environs.

Which left -- wallowing in the megabucks -- Byrd, Appropriations Chairman Warren G. Magnuson (D-Wash.), a handful of senators eager to attach home-state favors to the bill, and a brigade of assistants.

Deep into the night they went, debating and arguing amendments, and assuring that the supplemental money bill will ballon well beyond its already historic character as the largest ever to hit the Senate.

Among its vital moneys: federal salary increases, Medicaid, Chrysler Corp. loan guarantees, trade adjustment assistance, Mount St. Helens volcano disaster relief, Cuban refugee aid, student loan insurance, black-lung payments for disabled coal miners, child nutrition and dozens more.

They will continue the debate at 8 this morning, with Byrd hoping to have the bill ready for quick dispatch to the House so conferees can be named by late afternoon.

And if there's time, the Senate may take up the Budget Committee's reconciliation bill that would save $6.4 billion in next year's federal budget.

If it really matters, that is, after Antic Thursday.