At Christie’s, he managed sales of rare books, manuscripts and documents by the likes of da Vinci, Lincoln and Kerouac. On TV, he lent his eye to “Antiques Roadshow.”Christopher Coover, who made a career out of reading other people’s mail as an expert in rare books and manuscripts at Christie’s Auction House, where he oversaw the authentication, appraisal and sale of documents ranging from the original texts of Jack Kerouac’s “On the Road” to George Washington’s annotated copy of the Constitution, died in Livingston, N.J., on April 3, his 72nd birthday.The immediate cause was pneumonia complicated by Parkinson’s disease, his son, Timothy, said.As a connoisseur of curios, Mr. Coover was enlisted as an appraiser for the PBS program “Antiques Roadshow,” where at a single glance he could transform an all-but-forgotten autographed book or letter, retrieved from a starry-eyed guest’s basement or attic into a valuable historical heirloom.“The sense of discovery never fails,” he told The Colonial Williamsburg Journal in 2011. “I like the challenge of seeking out the larger background, the hidden meanings and connections of a given document. This means I am sometimes overworked, occasionally out of my depth, but never bored.”Mr. Coover in 2004 with letter from Abraham Lincoln to Ulysses S. Grant. “The historical nuggets in original manuscripts are often buried, but rarely deeply,” he said. Ruby Washington/The New York Times)For 35 years as senior specialist in the Rare Books and Manuscripts Department at Christie’s in Manhattan, he would authenticate material offered for auction, describe its provenance and history for the catalog, and suggest the opening price.Among his career milestones was assisting in the sale of the oil magnate Armand Hammer’s copy of an early 15th-century scientific manuscript by Leonardo da Vinci — known as the “Hammer Codex” — to Bill Gates, the Microsoft chairman, for a record $30.2 million in 1994.Mr. Coover appraised and managed the sale of the publisher Malcolm Forbes’s collection of American historical documents in six auctions from 2002 to 2007. The sale set records for letters by 15 presidents and generated more than $40.9 million. The sale’s catalog included a manuscript of Abraham Lincoln’s last speech; Robert E. Lee’s message to Ulysses S. Grant, in which he said he was ready to discuss the “cessation of hostilities” to end the Civil War; and a 1939 letter from Albert Einstein to President Franklin D. Roosevelt encouraging the American effort to build the atomic bomb.Mr. Coover also wrote the catalog for the sale of Kerouac’s “On the Road” manuscript, typed on a 119-foot-long roll of United Press Teletype paper ($2.4 million); and appraised and managed the sales of Lincoln’s 1864 Election Victory speech ($3.4 million), Washington’s letter on the ratification of the Constitution ($3.2 million), Washington’s personal annotated copy of the 1789 Acts of Congress ($9.8 million) and the original manuscript of James Joyce’s “Ulysses.”Christopher Coover was born on April 3, 1950, in Greeley, Colo. His parents left his middle name blank on his birth certificate so that he could choose one later himself. He selected Robin, from his favorite childhood books; his full name became Christopher Robin Coover.The family moved shortly afterward to Poughkeepsie, N.Y., where his parents were hired by Vassar College — his father, James Burrell Coover, as a professor and music librarian, and his mother, Georgena (Walker) Coover, as a teacher and specialist in early childhood education.Chris attended Arlington High School in Poughkeepsie before his father took a teaching post at the State University of New York at Buffalo, bringing his family with him. Chris graduated from Kenmore West High School in Buffalo. He earned a bachelor’s degree in musicology from SUNY Buffalo in 1973.He subsequently formed a band that played at weddings and other receptions, drove a school bus, worked for The New Grove Dictionary of Music in London and in the rare books room of the Strand book store in Manhattan before he was hired by Sotheby’s in 1978.He left for Christie’s in 1980. While working there, he earned a master’s in library science from Columbia University. He retired in 2016 as senior specialist and vice president of the auction house.Mr. Coover also lectured on American documents and built his own collection of literary and historical books and manuscripts, which he donated to Columbia.Mr. Coover, who died in a hospital, lived in Montclair, N.J. In addition to his son, he is survived by his wife, Lois (Adams) Coover; a daughter, Chloe; and two sisters, Mauri and Regan Coover.In the authentication of documents, Mr. Coover said, most forgeries are readily apparent, typically because the paper cannot be faked. Such was the case with a supposed 1906 first edition of “Madame Butterfly,” purportedly signed and dedicated by the composer, Puccini, which a reader of The Chicago Tribune asked Mr. Coover to authenticate.Sight unseen, he was able to recite the dedication, in Italian (he said he had seen 10 to 15 copies of the score with the same words), and identified the reader’s find as only a photolithographic copy.Then again, he said, ordinary-looking documents can contain surprises.“An otherwise boring diary or series of family letters mainly recording weather and local news may contain a long description of an election campaign, demonstrations against the Stamp Act, the convening of the Confederacy to draft a constitution, or a raid by Pancho Villa,” he told the Williamsburg journal.“The historical nuggets in original manuscripts are often buried, but rarely deeply,” he added. “I once discovered an exceptional letter of Ethan Allen at the bottom of a pile of old deeds, copies of minor poetry and otherwise uninteresting papers.”Assessing the monetary value of an item is highly subjective, he said.“Family bibles and birth and death records are valuable for their genealogical information, but they have very little commercial value,” he was quoted as saying in Marsha Bemko’s book “Antiques Roadshow: Behind the Scenes” (2009), “and I think it is a shame to see little old ladies waiting in line for hours while hefting a 40-pound Bible that is worth very little monetarily.”“You have to trust your innate instincts and perception of the size of the potential market,” he said. “The value of some letters and documents can only be determined by letting the free market operate, at auction.”Mr. Coover recalled that in 1992 he was asked by the grandson of a woman who had recently died to appraise her collection of books. He visited her Manhattan apartment and immediately realized that the books were not very valuable, but as he was leaving, the grandson asked him to look at some papers in a tattered Manila envelope.Inside, Mr. Coover told The Times in 2004, he found an old black leather book with the word “autograph” embossed in gold on the cover. On the very first page, he recognized Lincoln’s signature, followed by the last handwritten paragraph of his Second Inaugural Address. He told the young man that that one page alone was worth at least $250,000. When it finally went to auction, it sold for $1.2 million. More