A photograph yesterday with an article about departing members of the 98th Congress was of William Ratchford, head of the Maryland Department of Fiscal Services, not Rep. William R. Ratchford (D-Conn.).

A few weeks ago, congressional authorities gently told Rep. Jerry M. Patterson (D-Calif.), who lost his reelection bid, to vacate his Capitol Hill office so it could be repainted for its next occupant.

For days, until he finally moved out last week, Patterson had to operate out of cardboard boxes, a humble and harried ending to a 10-year House career.

But Patterson, like many other departing members of the 98th Congress, quickly discovered that, a few bumps to the ego aside, an ex-congressman is a valuable commodity in a city that runs on political connections, access and inside information.

On Jan. 3, when the 99th Congress is sworn in, Patterson will be settling in as a partner in the Washington office of a California law firm. There, he expects to work with and lobby for some of the financial institutions whose representatives testified before the House Banking, Finance and Urban Affairs Committee on which he served as a subcommittee chairman.

For his efforts on behalf of these and other clients, Patterson can expect to earn between $100,000 and $200,000. The man who defeated Patterson in the election last November, former representative Robert K. Dornan (R-Calif.), will be paid $75,100 a year in the House.

While many of the 50 departing members of the 98th Congress are returning home to retire or resume professions they practiced before entering politics -- ranging from farming to dentistry -- at least one-fourth have chosen to remain here.

They hope to cash in on their time and expertise on Capitol Hill by becoming Washington lawyers, lobbyists, consultants or high-ranking federal employes, often representing groups that they once helped to regulate. The U.S. Association of Former Members of Congress lists as many as 130 ex-lawmakers who succumbed to "Potomac Fever" and the lure of hefty salaries and never left Washington.

"It's a canard that members of Congress are in Congress because they can't get a job," said retiring Rep. Barber B. Conable Jr. (R-N.Y.), a 20-year House veteran and ranking Republican on the powerful Ways and Means Committee. "That's certainly not the case when they leave. I've never known anyone to leave Congress and go to a lower-paid job."

Conable plans to stay here a few months to work on a book at the American Enterprise Institute but then to return to western New York to teach and serve on corporate boards. He said he was astounded at the number of offers he received from law firms, consultants and trade associations to be their Washington insider.

"Your marketable skills are in government," said Rep. William R. Ratchford (D-Conn.), another Election Day casualty. "I have two children in college, and that doesn't allow you to contemplate future employment too long. You're out of Congress Jan. 3, but the tuition bills keep coming Jan. 4."

Ratchford and Rep. Ray Kogovsek (D-Colo.), who retired, are joining Gold and Leibengood, a lobbying and consulting firm put together by former associates of retiring Senate Majority Leader Howard H. Baker Jr. (R-Tenn.).

Baker, preparing to consider a race for the presidency in 1988, may be the most marketable member of the 98th Congress. He reportedly will earn as much as $800,000 annually as a lawyer and influence broker in the Washington office of the Texas law firm of Vinson & Elkins.

Four other departing senators, Armed Services Committee Chairman John G. Tower (R-Tex.), Foreign Relations Committee Chairman Charles H. Percy (R-Ill.), Jennings Randolph (D-W.Va.) and Roger W. Jepsen (R-Iowa), also are planning to stay here, according to aides.

Percy and Jepsen, both defeated for reelection, have not settled on new employment, although Percy may be in line for an ambassadorship. Tower, who retired, plans to teach a few days a month as a guest lecturer at Southern Methodist University, but he and his wife will live here, and he is said to be interested in a high administration appointment.

Randolph, who came here in 1932 as a House member and retired this year, has decided to pursue "a new career" here, according to an aide, who added that the senator has not said what that career will be.

Sen. Walter D. Huddleston (D-Ky.), another election loser, has sent his files and official papers to the University of Kentucky, according to an aide, but has not resolved his future.

Sen. Paul E. Tsongas (D-Mass.), who decided not to run for reelection after discovering that he suffers from a form of cancer, is returning to Lowell, Mass., to practice law and serve on corporate boards.

On the House side, Rep. Tom Corcoran (R-Ill.), who gave up his seat in an unsuccessful primary run for the Senate, has been sworn in as a director of the Synthetic Fuels Corp.

Rep. Jack Hightower (D-Tex.), who lost a reelection bid and a seat on the House Appropriations defense subcommittee, is expected to practice law and lobby here, possibly for the defense industry, an aide said.

Rep. John N. Erlenborn (R-Ill.), retiring as ranking Republican on the House Education and Labor Committee, will also practice law and lobby here. One of his clients will be a consulting firm that deals with employe-benefit issues.

Erlenborn was an author of the 1974 law setting comprehensive standards for private employe pensions and fringe-benefit plans.

Rep. Lyle Williams (R-Ohio), defeated in November, has been interviewed for a possible high-level job at the Labor Department.

Rep. James M. Shannon (D-Mass.), who gave up his seat to run unsuccessfully in a Senate primary, will join the Boston law firm of Hale & Dorr, which has a Washington office. Shannon, who says he is interested in running for office again, said he will spend most of his time in Boston, where his potential constituency is.

Among those going home are Reps. Kent Hance (D-Tex.), who also lost a run for the Senate and will return to Lubbock to practice law; Donald J. Albosta (D-Mich.), who lost and will return to his family farm, and Daniel B. Crane (R-Ill.), defeated after being censured by the House in July 1983 for sexual misconduct with a female page in 1980. Crane will reportedly return to Danville, Ill., to his dentistry profession.

Two North Carolina freshman Democrats caught in the Reagan landslide, Reps. Robin Britt and James McC. Clarke, are returning home to contemplate running again in two years. Britt will practice tax law, and Clarke returns to his farm.

Some lawmakers have no idea what they will be doing Jan. 3.

Rep. Frank McCloskey (D-Ind.) is awaiting an election recount in his district, and McCloskey's GOP opponent is reported leading by about 30 votes. Final results are not expected for weeks, and the House may have to decide the winner.

Does McCloskey have any idea what he'll be doing next year? "No," he sighed. "None at all. It's the longest election night in history."