I'm continuing to re-read the Narnia books. Will have more to say about that sooner or later, but for now, here's a link to an online copy of C. S. Lewis's outline of Narnian history (contains major spoilers for the whole series). Particularly useful for determining intended ages for the various human characters in the various books. Here's another copy, which may have slightly different wording (I didn't compare them, but someone commented on wording being different in different online copies of this). There's another copy formatted in plain text, but I'm not gonna link to that, 'cause whoever typed it in did such a bad job of proofreading that (for example) "Caspian" is spelled as "Caspain" throughout.
I gather that Lewis wrote this timeline after writing all the books, so he may've done some retroactive jiggering of dates. For example, according to the timeline, Edmund was born in 1930 and Lucy in 1932, but I seem to recall there's an indication somewhere that there's only a year's difference in their ages; of course, Edmund could've been born in late 1930 and Lucy in early 1932.
I was kind of surprised to see that Eustace is younger than Lucy. I could've deduced it from the ending of Dawn Treader, when--y'know, there's no way I'm going to get through this entry without spoilers for various of the books, so consider this a spoiler warning.
At the end of Dawn Treader, we learn that Lucy and Edmund are too old to return to Narnia, but maybe Eustace isn't. I was surprised that Eustace was younger than Lucy, 'cause I thought he was acting older (in an obnoxious sort of way) at the beginning of the book. But if we're just talking chronological age here, then it's kinda inconsistent anyway, 'cause Peter's about 13 when he first goes to Narnia, and Lucy's only about 10 at the time of Dawn Treader.
Lewis tries to finesse this at the beginning of Silver Chair by suggesting that the idea is actually that Lucy and Edmund had been to Narnia three times and that's all they get. I guess that's a little more reasonable.
But really I think Lewis was just being inconsistent, and there are several other inconsistencies in the books, and I'll just have to live with that. It's not really such a big deal.
But I do sorta feel like some of the inconsistencies are things an editor should have noticed at some point. Like, in Prince Caspian, there's a line that suggests that the Pevensies' arrival at Aslan's How is the same day that Caspian blew the horn, only it's actually been something like three or four days since they arrived in Narnia.
While I'm looking at this stuff critically, I may as well mention that I'm struck by just how often Aslan steps into the books and makes various things happen. (Though to be fair, most of the time when he does this it's just to provide guidance to the characters who are faithful and/or receptive.) The plots and structures of these books are a mess from the point of view of modern accepted wisdom in the sf writing community. Literal deus ex figurative machina, over and over again. If Lewis took these manuscripts to an sf writing workshop, they'd tell him "Nice start, but better go back and write a few more drafts." And yet, these books are still in print after 50+ years, and are still loved by most of the people who read them. And for that matter, I'm still enjoying them here on my third? fourth? read, despite my criticisms. So I can't say Lewis was wrong to do things this way; I'm just surprised at how blatantly these classic books violate the supposed "rules" of how these things are supposed to be done.