David Starr Jordan announced an exciting breakthrough in Popular Science Monthly in 1896: He’d asked seven people to think of a cat and then used a special device to capture their mental images and combine them into a composite picture, “the impression of ultimate feline reality.”

Jordan had intended the piece as a “gentle satire” of then-prevalent experiments in mental photography, but to his horror the readers took it seriously:

One clergyman even went so far as to announce a series of six discourses on “the Lesson of the Sympsychograph,” while many others welcomed the alleged discovery as verifying what they had long believed, and an eminent professor soberly opined that my reputation as a psychologist would not be enhanced by such discoveries!

He later wrote that the experience had taught him two lessons: “first, that very few people ever read a sensational article through to the end, even much beyond pictures and headlines, and second, that with Dr. Holmes, I should never again ‘dare to write as funny as I can.’”

Readers of the Madison, Wis., Capital-Times had a scare on April 1, 1933 — a front-page photo showed that the state capitol had collapsed.

The words “April Fool” appeared in small type both in the caption and at the end of the accompanying article, but readers were not amused.

“There is such a thing as carrying a joke too far,” wrote one, “and this one was not only tactless and void of humor as well, but also a hideous jest.”

Published in London’s Wide World Magazine in 1898, Louis de Rougemont’s adventures in Oceania made a sensation: He had witnessed octopus attacks on the pearl fishers of New Guinea, rode turtles while a castaway on an anonymous Pacific islet, and spent 30 swashbuckling years as a god-king among Australian cannibals. Here he’s beset by migrating rats:

It was impossible for me to observe in what order the rats were advancing, on account of the great stretch of country which they covered. Soon, however, their shrill squeals were distinctly heard, and a few minutes later the edge of that strange tide struck our tree and swept past us with a force impossible to realise. No living thing was spared. Snakes, lizards–ay, even the biggest kangaroos–succumbed after an ineffectual struggle. The rats actually ate those of their fellows who seemed to hesitate or stumble. The curious thing was that the great army never seemed to stand still. It appeared to me that each rat simply took a bite at whatever prey came his way, and then passed on with the rest.

In September an F.W. Solomon wrote in to say that he recognized the author — he was a Swiss manservant named Louis Grien whose nearest approach to the Outback had been a stint as butler to the governor of Western Australia. After some temporizing, De Rougemont vanished; he reappeared the following year in a South African music hall, billing himself as “The Greatest Liar on Earth.”

See Romance at Short Notice.

After discovering a talent for forgery during the Civil War, James Reavis headed west and started one of the most ambitious hoaxes of all time. He invented a Spanish nobleman named Miguel de Peralta, devised his entire family tree, and began assiduously forging documents claiming 10 million acres of prime Arizona land for the don’s descendants. Then he traveled throughout Spain and Mexico, carefully seeding libraries and archives with the forged deeds, mortgages, and wills.

When all was ready, he went before the U.S. surveyor general in 1881 and showed that rights to these lands now belonged to him. He imposed taxes on residents throughout Arizona, including the Southern Pacific Railroad and the Silver King Mine, but when their lawyers sought to challenge the claims they found Reavis’ carefully forged documents on file.

The ruse made Reavis one of the richest land barons in Arizona, and soon he’d bought mansions in New York, Washington, St. Louis, and Mexico. But it all lasted less than 10 years, unraveling in 1890 when a Spanish linguist detected the forgeries. Reavis served six years in prison and spent the rest of his life on the streets of Santa Fe.

In the 1840s P.T. Barnum found himself a victim of his own success. His New York museum of curiosities proved so popular that it was regularly filled to capacity and could admit no more customers.

Barnum studied the problem and hired a carpenter. Soon a new door appeared in the museum with a sign reading THIS WAY TO THE EGRESS.

Those who followed it found themselves on Ann Street.

Canada saw a sensation in 1836 — a woman named Maria Monk claimed to have been a nun in a Montreal convent where priests from the nearby seminary would enter through a secret tunnel, force sex on the terrified nuns, and dispose horribly of any resulting children:

[Father Larkin] first put oil upon the heads of the infants, as is the custom before baptism. When he had baptized the children, they were taken, one after another, by one of the old nuns, in the presence of us all. She pressed her hand upon the mouth and nose of the first so tight that it could not breathe, and in a few minutes, when the hand was removed, it was dead. She then took the other and treated it in the same way. No sound was heard, and both the children were corpses. The greatest indifference was shown by all present during this operation; for all, as I well knew, were long accustomed to such scenes. The little bodies were then taken into the cellar, thrown into the pit I have mentioned, and covered with a quantity of lime.

Awful Disclosures of Maria Monk became a bestseller, but an investigation showed that the whole thing had been a fake; Monk had apparently never even visited the convent. She fled to Philadelphia, wrote an unsuccessful sequel, had a child out of wedlock, and died in 1839.

“Spirit photographs” created by hoaxer William Hope in 1919.

From left: Mr. and Mrs. Gibson with their deceased son; Mrs. Longcake with her dead sister-in-law; the Rev. Charles Tweedale and his wife, with her father.

Arthur Conan Doyle (below, center) defended Hope even when skeptic Harry Price had shown that he was manipulating his plates. “The credulity of dupes,” wrote Edmund Burke, “is as inexhaustible as the invention of knaves.”

In 1885, explorer Richard Willoughby claimed to have discovered a wonderful mirage above Alaska’s Muir glacier: He’d seen a modern city, he said, with buildings, church towers, vessels, even citizens. This photograph sold “like hot cakes” in the summer of 1889, and Willoughby sold the negative to a San Francisco photographer for $500.

There it all unraveled. An American consul, home from England, noted that the “silent city” bore a striking resemblance to Bristol. It turned out that Willoughby had paid an English tourist $10 for an overexposed photo of his hometown, and the rest was hot air. Still, he deserves credit for invention.