Old-time printers used to recite or sing this heartfelt rhyme:
That was back in the days when a printer had to set every word by hand, carefully picking out each metal letter one at a time from a box of two cases (hence the terms upper and lower case). "There was a convenient belief among printers that there was a special devil in every print-shop," says Chas. Jones, of Britain's WritersServices.com.
"At night, or when the printer was not watching, this pesky demon would iuvert letters, mizspell a word or perhaps remove an entire or even a complete line... Mistakes were inevitable, and the printer's devil took the blame."
Chas. kindly gave us permission to copy the image of the Printer's Devil displayed at the top of this page. "It's perched outside a shop in Stonegate, Yorkshire, England" he said. "I think I censored the original! It marks the place where Tristram Shandy was first published."
The Life and Opinions of Tristram Shandy, Gentleman was a novel written by Laurence Sterne in 1759. Wikipedia says "its bawdy humour was popular with London society, and it has come to be seen as one of the greatest comic novels in English, as well as a forerunner for many modern narrative devices."
Probably the first and one of the worst typographical errors occurred in 1631, when printers of what is now known as the "wicked" bible were fined 300 pounds sterling. In printing the Ten Commandments, they had omitted the vital word “not” so that the verse read “Thou shalt commit adultery." A thousand copies were ordered to be destroyed, but a few survived. Today they're worth thousands of dollars to collectors.
Thanks to the computer, typographical errors (now called typos) are much more frequent these days. It's rare to find a web page without them. Most blogs are full of them, because of bad spelling, ignorance, or carelessness. But it's easier to blame Typo, the printer's devil, gremlins, leprechauns, or even those pesky Norwegian trolls.
In the old days, a printer's devil was the name given to the newest apprentice in a print shop, the unfortunate lad who had do all the odd jobs, ending the day with ink all over his hands, face and clothes. No wonder he would have scattered a lot of those typos in revenge!