We learn in chapter 5 that there are seventeen Sickles to the Galleon. Given that fact, it seems strange that Harry overheard someone saying that dragon liver was for sale in Diagon Alley for "seventeen sickles an ounce." Why wouldn't they just say that it cost one Galleon?
In the summer of 2004, Bloomsbury released new editions of the Harry Potter books. These new editions featured a slew of changes to the original text. Some of the changes were simple fixes for typos. For example, on the third line of page 15 of Philosopher’s Stone, the word Potter’s was changed to Potters’.
For fans, however, the far more interesting changes were the ones that fixed errors. Many of these errors had been discovered and discussed for several years in online discussion groups such as Harry Potter for Grown-Ups, so in some way the 2004 changes seemed to be a response to fan input. Okay, that was probably not true, but fans did feel some sense of accomplishment when they saw that the errors they’d spotted had been fixed.
Here’s a list of the biggest error fixes in the first book:
Sirius and his motorcycle
In the original text of chapter one, Hagrid leaves Privet Drive saying “I’ll be takin’ Sirius his bike back.” As the story developed over the next four books, particularly book three, the details of Sirius’s actions immediately after James and Lily died changed quite a bit. As a result, it didn’t seem logical that Hagrid would have said that. So in the 2004 edition, Hagrid says “I best get this bike away.”
The price of dragon liver
We learn in chapter 5 that there are seventeen Sickles to the Galleon. Given that fact, it seems strange that Harry overheard someone saying that dragon liver was for sale in Diagon Alley for “seventeen sickles an ounce.” Why wouldn’t they just say that it cost one Galleon? This minor error was fixed in the 2004 edition by changing the number in the sentence so it now reads: “Dragon liver, sixteen Sickles an ounce, they’re mad…”
How long has Nearly-Headless Nick been dead?
Originally, the book has Nick saying “I haven’t eaten in nearly four hundred years” at the Welcoming Feast. However, in book two he celebrated his 500th Deathday party. So in the 2004 edition his line in book one was changed to say “I haven’t eaten in nearly five hundred years.”
Pubs in Hogsmeade
Hagrid tells Harry that the Hog’s Head is “the pub down in the village.” In book three, though, the pub the kids visit in Hogsmeade was The Three Broomsticks. Clearly there is more than one pub in the village, but that line in book one makes it sound like The Hog’s Head is the only one. So they changed the line to read “… yeh get a lot o’ funny folk in the Hog’s Head – that’s one of the pubs down in the village.” Problem solved.
There are two problematic phrases in the original version of Philosopher’s Stone which describe chess moves. Here’s how they were fixed in the 2004 edition:
“Well, Harry, you take the place of that bishop, and Hermione, you go next to him instead of that castle.” But the castle and the bishop are not next to each other on the chessboard at the start. The knight stands between them. So the line was changed to say “Well, Harry, you take the place of that bishop, and Hermione, you go there instead of that castle.”
The other line is “I take one step forward and she’ll take me–that leaves you free to checkmate the king, Harry!” Ron, though, is playing the part of a knight, and knights never move only one space. They move in a four-space L-shaped pattern. This line was adjusted to say “I make my move and she’ll take me–that leaves you free to checkmate the king, Harry!”
Most readers nowadays haven never seen an original edition of the early Harry Potter books, so these errors haven't even existed for them. But for fans back in 2000, when the Lexicon grew out of online discussions, these errors were bandied about quite frequently. They formed the basis for a variety of interesting theories and debates. So the 2004 updates to the novels were a very big deal.