There is a book on sale at the souvenir stands of Pimlico Race Course this 103rd Preakness week. Two bucks. There are reasons to buy it.

"The Preakness: A History" tells more about the first 99 Preaknesses than has ever been known by homosapiens about a single horse race in all the centuries since Philip of Macedon gave Alexander a leg up on Bucephalus and told the boy to take him for a two-minute lick.

Josph J. Challmes' history offers more detail, perhaps, than you average homo sapiens would care to absorb, about all those Preaknesses. But it is a limited edition - limited to the 3,000 copies that sat in the author's garage after the first 2,000 were sold (or given away) - and it is selling for 40 cents on the dollar, a better price than they made Secretariat at Pimlico.

Besides, people are always saying at cocktail parties that they'd like to write a book in the worst way, and Joe Challmes may have done it: with a full-time job, a pregnant wife working as a nurse, a 2-year old child and a six-month deadline, he betook himself to the ordeal of microfilm to research a book nobody had asked for, or paid for. At 2 a.m. on Jan. 1, 1975, the deadline date, Joe Challmes put a period and a close-quote after a final quotation from Secretariat's mistress, Penny Tweedy, finished off the fifth of drambule and passed out for 29 hours.

So, if you think it is Trivia that Maryland Gov. Oden Bowie (1869-72) had eyes that were deep-set and small, consider the admonition of Willy Loman's wife to her sons: a terrible thing has happened to Joe Challmes, and attention should be paid to him.

As a 25-year-old rewrite man for the Baltimore Sun, Challmes in June 1975 was working an evening shift; his wife was working nights, 11 p.m. to 7 a.m. Each morning, for weeks and weeks, he would arise too early and carry his looseleaf notebooks to the Enoch Pratt Library, where there was microfilm of the New York Times as well as the Baltimore paper.

George Lorillard, scion of the wonderful people who gave us Newport Lights and owner of the winners of the 1878-79-80-81-82 Preaknesses, was the Ted Turner of his time, winning the New York Yacht Club Regatta in '68, his first try. Challmes filled three notebooks, longhand, with that sort of information.

His history includes fashion and social notes. Ladies among the 40,222 attending Faultness' 1947 Preakness favored a patent-leather "sailor" hat that had been in vogue at the turn of the century. Rooting for Iron Liege a decade later was Adm. Gene Markey, who married the widow of Calumet too late to share in any of its Triple Crowns.

The drudgery of gleaning these iotas was taking its toll - on Challmes and his wife - by December. So he sent his wife home to her mother, with the 2-year-old Mary Rebecca, took three weeks' leave from his job and began to write.

"The last three weeks," he recalled, 'I wrote from 8 a.m. to 4 a.m. I was going on gin and coffee."

Why? Because he is a racetrack degenerate and a Baltimore chauvinist (the latter sticks out all over the 220 pages), not necessarily in that order. Born in Govans on the north side, now a slum and then a blue-collar neighborhood, Challmes found his way to Pimlico as a teenager. His parimutuel habit helped, rather than hindered, his progress through Johns Hopkins, Challmes says, citing one glorious day of can't-miss handicapping at Penn National.

"The book was a labor of love," Challmes said with understatement. "I got interested in the history of the city . . ." It is, Challmes' book asserts, "a city vitally alive with the conveniences of New York, but not half the problems.' And its "truly run" race, he concludes geometrically, is "the most significant race (of the Triple Crown) in determining a champion."

Challmes' omnibus reporting does show how swiftly times change. Here is Chick Lang in 1956, agent for jockey Bill Hartack, delivering the clinche that the sharper turns at Pimlico give Hartack's mount, Fabius, a better chance than he had at Louisville. Fabius won. Now Charles J. (Chick) Lang, general manager of Pimlico, says the turns aren't all that sharp, and anyway that's a cliche.

Then Venetian Way won the 1960 Derby with the analgesic drug Butazolidin and was badly beaten in the Preakness without it. "Nobody's suggesting," suggested New York Herald Tribune columnist Red Smith, "calling the Dergy the Drugstore now 10 or 11 of every 12-horse field in outlawed Butazolidin for racing purposes and the ambiguity loused up the '68 Derby. Still later Maryland, took the lid off Bute and Lasiz as well, and now 10 or 11 of every 12-horse field in the Free State go to the post containing something to make them feel better.

Now whose races are "truly run'?Will some New York wise guy refer to the Old Line State as the Mai Line State?

Joe Challmes will come up with an answer - if he has to write all night.