The Senate lectures presidents and Cabinet officers, attempts to make foreign and domestic policy, accepts or rejects treaties, votes billions for the public purse and is, to all appearances, a very important and powerful institution.

What it can't do is feed itself without a subsidy.

Its network of restaurants and cafeterias and snack bars runs in the red every year ($240,000 in 1975) and the deficit, of course, is made up by the taxpayers. It's like those $3 haircuts at the Capitol.

The House of Representatives had the same failing for many years but since 1973 the House has been able to break even on its feeding operations. Once in a while it shows a small profit, thanks, in part, to the dethroned Rep. Wayne Hays (D-Ohio), who was later better known for his efforts to pad members' allowance and benefits at the taxpayers' expense.

When Hays became chairman of the House Administration Committee in 1971, he assumed direct responsibility for the House restaurants. Within two years he turned the system's chronic deficits into a break-even operation.

What Hays did to achieve that turnabout was to cut the system's payroll, institute strict cost accounting and bargain furiously with food suppliers, according to Robert McGuire of the House Administration Committee.

What he did not do was increase prices or lower standards at the system's "flagship" restaurants, the two members' dining rooms on the first floor of the Capitol.

Those rooms still offer members and their guests above-averaged food and impeccable service in elegant surroundings - at bargain basement prices.

A recent menu offered a complete meal, appetizer through dessert, featuring either roast top sirloin of beef or chicken cordon bleu, for $3.95. The famous bean soup costs 45 cents for a generous bowl, and other soups are only slightly more expensive. Beer is available at 60 cents a bottle, and a small carafe of domestic wine costs $1.10. Coffee, served in an individual service at the table, is 25 cents, with unlimited free refills. The members pay no sales tax on the meal.

At those prices, the two House members dining rooms cannot be profitable.They lose about $300,000 per year, but the House makes up the loss on its less extravagant staff facilities.

The cafeterias and snack bars that serve House staff employees and the public provide average food at prices equivalent to those at other federal buildings.

The same situation - luxurious surroundings and low prices for members, ordinary fare and standard prices for others - holds true in the Senate, but that body has never been able to overcome its restaurants' deficits.

In 1975, the last full year of which data are available, the House restaurant system reported a profit of $534 on gross sales of $3 million. The Senate system lost $239,659 on gross sales of $2.5 million.

Jay Treadwell, an employee of the Capitol Architect's office who runs the Senate restaurant system, has no ready explanation for the difference in results. But Treadwell said his chief management goal is to "eliminate the drain on the taxpayers that our system is causing."

Maguire, of the House Administration Committee, suggested that the House restaurants' financial stability is due to the committee members' zeal to control costs.

"Chairman Hays, when he was her, and Dawson Mathis the Georgia Democrat who chairs the committee's Restaurant Subcommittee are very, very concerned about holding down the costs of the whole operation," Maguire said.

The Senate, on the other hand, seems concerned about maintaining the traditional standards of its dining areas.

Last March, when Capitol Architect George White went before an appropriations subcommittee to explain the Senate restaurants' financial status, he was interrupted by Sen. Ernest F. Hollings, (D-S.C.), who chided White on the decor in the members' dining rooms.

"We hope to increase the elegance all over," White assured Hollings.

One aspect of increased elegance in the Senate dining rooms is an imposing new menu that was introduced with the recent opening of the 95th Congress.

In place of the simple blue one-page "flyer" that had served for years, senators now choose their entrees from a portfolio menu that comes inside a thick white cover embossed with the Senate seal. The menu and cover are bound by a braided cord that ends in two purple tassels.

The text of the new menu relies heavily on the definite article.

Under a general heading. "The Fare," are sub-sections headed "The Grill," "The Eggs," "The Cheese and Fruit Intermission," and "The Dessert Cart."

Conspicuously absent from the new menu is the traditional recipe for bean soup, which had been printed on the previous menu every day.

Treadwell said the receipe is still available for those who ask for it, but he insisted it did not belong on the menu itself.

"Any dining room that has to dependon its bean soup recipe to draw customers can't be much of a place," he said.