I wonder if the author was thinking of 1899 as "the end of the last century." It can happen to people who lived much of their lives in the 20th century.
I was born not that far off the end of the last century and I didn't bat an eyelid at that, heh.
Even weirder is that we are currently in the '20s. That's always going to mean 1920s to me, but I imagine I'm going to have to get used to younger family & news etc. using it to mean 2020s in the not too distant future.
