Encyclopedias, being time sensitive, are the most ephemeral of imposing objects. Soon enough they become quaint, fussy, outdated, wrong. For the right reader, though, there is pleasure in wrongness, which is one of the theories behind Christopher Miller’s new book. The encyclopedic “American Cornball” arrives both outdated and in its ideal form: It’s a peculiar, enlightening book, an investigation of trivia, a strange history of American life from 1900 through 1966 (Miller’s self-imposed limit) and, as all single-author reference books are, a document of obsession.

“American Cornball” discusses off-color postcards, gag gifts, animated cartoons, newspaper comic strips, old comedies, comic books, humor magazines and sitcoms. But it’s not a history of any of these things. Its inspiration is something even less durable: the jokes contained therein. How and when did we come to find anvils not only funny, but the truest test of the Earth’s gravitational pull? What is limburger cheese, that exemplar of stench? What is the difference — in fact, and in risibility — between a hobo and a bum?

This book, arranged alphabetically from “absentminded professors” to “zealots,” attempts to examine the hoary wheezes of another time, and it’s a delight. You might think that a comic investigation of “bindlesticks” (the balloon-shaped bundles hung on branches that runaway children and hobos take on the road) or “middle initials” sounds dreary, but when Miller, whose previous two books are the novels “Sudden Noises from Inanimate Objects” and “The Cardboard Universe” (either of which would be a fine title for this book, too) is a brilliant writer, with a fondness for his own jokes and aphorisms: “Of course, even the most blameless euphemism will acquire connotations if it’s used enough,” he writes on the entry concerning “bosoms and breasts.” “That’s why euphemisms need to be replaced periodically, like air filters.”

The entry on “suicide” is particularly fine, with Miller charting suicide humor’s rise and fall. In a 1930 comic strip, Mickey Mouse tried to do away with himself with gas, a gun and gravity, and Miller tells us that “the first decade of the twentieth century was a heyday for jokes about small children taking their lives.” If that doesn’t sound funny, well, there’s a reason there’s not an “It’s a Grim World After All” ride at Disney World (even if some of us would go on it). The book is a strange side doorway to your memories of the cartoon, black-and-white movie, comic-strip, gag-gift world — all those things you laughed at without knowing why, exactly.

The material here is lowbrow (in no way an insult); its author is not. This is a book that compares a William Gass book to one by Mort Walker (creator of the comic strips “Beetle Bailey” and “Hi & Lois”) and, delightfully, finds the former wanting. (Walker’s splendid “The Lexicon of Comicana” was clearly an enormous influence on Miller.) He uses Rube Goldberg to plug Flann O’Brien. He observes that the act of defecation is acknowledged more among the highbrows than the low, “especially if the highbrow in question is Irish: like Swift, both Joyce and Beckett joked a lot about poop.”

Illustration a man rubbernecking from “American Cornball” by Christopher Miller. (Courtesy of Harper)

Indeed, perhaps the biggest difference between the highbrow and the lowbrow is not material, but the wishes of the highbrow to never be ephemeral, and the lowbrow’s resignation to that state. The authors of those naughty postcards with pictures of outhouses, portly gentlemen and ladies floating in the sea, men ogling pretty girls and the resulting “hat take” (Miller’s own term for a hat popping off a head in surprise) — never imagined their postcards would last the year, never mind find a place in this decades-later volume. Ephemera tells us the past was always more interesting and off-color than history class would let us think.

The book isn’t perfect. The librarian in me wished for a little less of the first-person Miller; the novelist in me wanted a little more. I found it puzzling just how many times Miller tells us in passing that he has never been married (at least five). On the other hand, there is the narrative that is at the heart of any single-author reference book, which is the story of a collector. Miller’s collections include joke postcards, artificial vomit and fake feces. It’s possible I am the only reader whose heart will sing at Miller’s fondness for synthetic ejectamenta, but I would happily have read more.

There are plenty of examples of obscure and fascinating things here — admirers of Foxy Grandpa can find him in these pages — but for well-known sources, Miller leans on his own loves a bit too hard. Of the great newspaper comic strips, he speaks mostly — and copiously — of the undeniably brilliant “Li’l Abner.” An Abbott and Costello aficionado — okay, me — might wonder why he mentions them only glancingly, when there are several places they would have been more germane than the Three Stooges, whom he trots out a tiresome amount, even for people who don’t find the Three Stooges tiresome.

What people laughed at in the past is not always pleasant or harmless (or even, as Faulkner might tell us, past), and Miller is careful to not expunge the hatefulness of some humor. There are separate entries for “Black people,” “Irishmen” and “Scotsmen,” but he missteps, I think, with “morons.” In that entry, he conflates stupidity with developmental disabilities and insists that comic fools such as Gomer Pyle, Krazy Kat and Barney Fife are representations of the intellectually disabled — whom he unhelpfully calls the “retarded” — offered up for laughter. The entry ends up feeling too self-righteous and too self-conscious: deadly in humor and in writing about humor.

Still, this is a book that can, in a single entry, track the history of flatulence in popular culture; tell us that Swift was the probable author of “The Benefit of Farting Explain’d” under the name Don Fartinhando Puffindorst; name-check the French music fart virtuoso Le Petomane by saying that his act in its heyday “would outgross Sarah Bernhardt”; discuss the disappearance of fart humor for much of 20th-century mainstream culture; explain that “Blazing Saddles” ‘did for flatulence what “Deep Throat” did for fellatio’; and end by revealing (to my happy edification) that describing a Bronx cheer as a “raspberry” is Cockney rhyming slang (raspberry “tart” for “fart”).

That is a perfect model of the narrowness of Miller’s focus and the broadness and mobility of his interests and knowledge. Not from the sublime to the ridiculous, perhaps, but sublimely ridiculous, and surely appealing to all brows, no matter their altitude.

McCracken’s latest book is “Thunderstruck & Other Stories.”

AMERICAN CORNBALL

A Laffopedic Guide to the Formerly Funny

By Christopher Miller

Harper. 530 pp. $35