"If it hadn't been for the diesel locomotive, all the railroads would have been bankrupt in a couple of years because the steam locomotive required a tremendous maintenance force," he said.

"Harry wrote a book, 'The Modern Locomotive Handbook,' that was used not only by our railroad but railroads all over the country," said Mr. McElvany.

When the B&O was contemplating power for operation of its trains, they turned to Mr. Eck.

"He'd conduct all the tests that told us how we wanted to run a train. He did it, and did it very well," said Mr. McElvany. "We would look at something and then put it up to Harry, who made it happen. He was just tops."

Mr. Eck retired in 1985, but made the transition into working as a docent at the B&O Museum, where he operated a collection of historic engines and spoke to visitors.

"Harry had great patience and the ability to judge how much technology a visitor wanted to know. He could go to any level and would tailor his remarks," said Courtney Wilson, executive director of the museum. "He was loved by visitors from all over the world."

"He knew working railroading and could communicate it beautifully," said Herbert H. Harwood Jr., a retired CSX executive and B&O historian and author. "He was a very impressive docent."

He had been a member of the Brotherhood of Locomotive Engineers and Firemen, and RABO, a B&O retirement organization, and since 1997 wrote a column for its quarterly newsletter, "Harry Eck Lets Off Steam!"

Reflecting on his career, he told a Washington Post reporter in 1998, "It's tangible stuff."

"Sounds, mostly: whistles, steam sounds, engines picking up speed, the wind at night, the clack of the wheels over rails or seeing the light from the locomotive through the pitch dark."

He added: "I remember it clearly — the freight trains, meat on the hoof from Chicago, the beer coming from St. Louis. You get a sense of the countryside when you're in the locomotive; you understand completely the weather, the temperatures and the aches of honest work."

Mr. Eck was a member of Catonsville United Methodist Church, 6 Melvin Ave., where services will be held at 10 a.m. Thursday.

Surviving are his wife of 53 years, the former Charlotte Exley; a son, Henry H. Eck of Catonsville; a daughter, Mary Elizabeth McFarland of Havre de Grace; and two grandsons.