Lawrence Ritter searched out the survivors and got their croaking old voices on tape. Bud Greenspan raked the files and raided the dilm libraries. Between them, writer and producer, they come up with "The Glory of Their Times," a full-hour history lesson, a learning experience.

It is a filmed-for-television flash back to the grimy, turn-of-the-century days of baseball when big-league ball-players were regarded as toughs and unwelcome at first-class hotels, when they walked from their rooming houses to their jobs in the wooden ball parks of the big cities, when a $3,000 salary was common pay for the times (1904-16).

It was filmed in 1969, based on the 1966 est-seller by Ritter, but pride-fully withheld by Greenspan until some network would give it prime time. Public Broadcasting took the cance, and has a winner whose ratings are heded out of the park. The program will be repeated at 1 p.m. today on channel 20.

The timing of the network was exquisite. "The Glory of Their Times" is now delivered with a special thrust in this year of baseball's free-agent orgy when the game's new fat cats are the athletes; when one outfielder (Reggie Jackson, who never his 300 in his life) could demand and get a Rolls Royce as a fringe benefit for signing a $2.9 million contract; when a mere relief pitcher could get $2 million from the Red Sox.

Twas not ever thus, "Glory of Their Times" is telling us with its snippets of ancient baseball films of surprising quality, and the thinning voices of eager old ballplayers telling of the good ol' days. For the baseball fan,, it has to be a one-hour fascination. For the super annuated it is pure nostalgia. For everybody, it is a titilating study in roots.

John McGraw, Christy Mathewson, Ty Cobb, Walter Johnson, Honus Wagner and Babe Ruth are alive again in their funny, buttoned uniforms. So are the funny, leato ball parks, rung by carriages in the outfield, with the grandstands packed by derbied fans paying 75 cents to yell their heads off.

Filmed snippets of the fence advertising in the old parks tell what Americans were wearing at the turn of the century: "Kuppenheimer Clothes." And what the he-men were chewing: "DEVIL Chewing Tobacco." And what they were shaving with: "Gem Double Life Blades" and holding up their stockings with "Boston Garters, of Course." And for the ladies: "Mrs. Winslow's soothing Syrup."

And while McGraw was winning all those pennants for the New York Gilants, what else was happening? Nicely worked into the film was the New York Times headline "The Titanic is Sinking," and the William Jennings Bryant "Cross of Gold" speech and Teddy Roosevelt's "Give 'em Hell" speeches . . . and what was Orville Wright doing in 1908 while Fred Merkle was committing his famous fail-to-touch second base boner? The film shows Orville trying to make an air plane stay up for 60 minutes for the U.S. Army.

For the pitchers, no new shiny white baseballs. After being tossed once around the infield following an out, each baseball bore the stains of tobacco juice spat on it by the first, second and third basemen, plus the shortstop.

"It came up to the hitter as black as the ace of spades," testified Fred Snodgrass of the old Giants.

If the film is heavy on McGraw, well, he was Mr. Baseball in those years. Legends grew up under him: Mathewson, his pride, the college football and baseball hero from Bucknell, who came up in 1900, and wom 30, 33 and 32 games in a three-year span and gave baseball a respectability it did not know before: "Young ladies could now ask their escots to take them to the Polo Grounds to see that college boy play," the narrator said.

"The Glory of Their Times" pegs Walter Johnson as everybody's nice guy. The day after Smokey Joe Wood of the Red Sox stopped Johnson's 16-game winning streak, 1-0, he said, "Awshucks, Johnson would never lose a ball game if he played for a good team." And what did nice guy Johnson, the fastest pitcher in baseball say of Wood? "Aw shucks, he's faster than I am."

And what did Edd Roush say about Jim Thorpe and his brief career with the Giants? "He's the fastest man I ever saw, but let's face it, the Indian couldn't hit that curve ball." And what did Harry Hooper, his Boston teammate say about Babe Ruth? "He didn't like to be called the 'Big Baboon.'"

Snodgrass of the Giants said it wasn't all his fault they lost the 1912 pennant to the Cubs even if his muff of that fly ball put the winning run on second base. "How about that foul pop Chief Meyers didn't get to? Mathewson was holldering 'Meyers, Meyers!' While the ball was dropping right in front of Merkle, who could'a caught it."

Ty Cobb came along in 1905, two years before Johnson. And how was Cobb regarded by his fellow players? "He never had a friend in baseball. He wasn't as good a ball player as Hans Wagner," testified the voice as Sam Crawford, Cobb's teammate on the Detroit Tigers.

But pitcher Sad Sam Jones testifies for Cobb as a great and gutty ballther side of the bag, and he'd cut ya if player. "He had speed sliding to ei-ya got in his way. He'd cut ya." And what did Cobb say to Wagner in the World Series of 1909 between the Tigers and the Pittsburg Pirates when Cobb was on first base? He yelled, "Hey, Krauthead, I'm coming down on the next pitch, so get outta the way." Cobb went and Wagner put a tag on him that necessitated three stitches in Cobb's lip and some dentistry. This was the Glory of Their Times.