I've just downloaded an anthology that goes by the rather boring title of
Up and Coming: Stories by the 2016 Campbell-Eligible Authors. I'd say that this is a must-download for SF and Fantasy fans. It is free and, as far as I can see, perfectly legal; but you do need to get your skates on - it's only available until the end of this month.
It is also massive, about 1.1 million words (which comes to 4400 pages at 250 words per page). But what intrigues me are the relative sizes of the epub and mobi versions. The epub version is 3.2 MB but the mobi version is four times the size at 12.3 MB. Now, I'm aware from converting the occasional epub to mobi in Calibre that the mobi version always ends up rather larger. But four times larger - this does seem rather extreme! Can anyonone explain the difference?