The Accuracy of Novels

I don't mean how accurate the facts contained therein may be but how accurately your edition of a novel is represented according to the author's original text. Take the infamous Great Illustrated Classics editions for example.

GIC published The Time Machine a while back since it's in the public domain just about everywhere right now. It'll be PD in the EU around 2017. But they changed the text without really letting anyone know. But this wasn't the first time the text of The Time Machine was altered upon publication.

The Time Machine was first published as a series between 1894 and 1895. But even back then it was altered before reaching the public's eyes, for an entire chapter was excised because it was thought too harsh or depressing or just too shocking for the readers of that time. You can read this "lost" chapter here.

But, the GIC edition did something even more sinister in my opinion; it ADDED an entire chapter to the novel (and changed the ending). This chapter, added years later...

[Tells of a time] in which the Time Traveller blunders into a highly advanced future society where time travel is illegal. The time machine is confiscated and the Traveller is arrested, but he eventually escapes after one of the future men attempts to steal the time machine.

It makes you wonder just how complete or at least what version of a novel you have and have read is. One red flag unfortunately may be the simple fact that the novel is now in the public domain.