In the Slocum case, the proper way to handle it would be with a copyright notice that said: introduction copyright 1956. To just copyright the whole book would be a sloppy way of handling it, and I would be surprised that a specialty reprinter like Dover would do it that way.
I found on my shelves a 1960 Dover edition of The Fourth Dimension Simply Explained and the notice reads:
No copyright is given at all.
On the other hand, my copy of The Origin of Species, a facsimile edition put out by the British firm of Senate, says:
In the U.S. you can extend copyright to display - the fonts and art direction of pages – so that no one can just photocopy your pages and put it out as their own work, but this is a facsimile so I don’t see how copyright would be applied to it. Maybe UK law is different.
VernWinterbottom’s point that public domain works do not come back into copyright just because they are republished or included in a compilation is completely correct. Once in the public domain always in the public domain.
(Except that when the UK extended its copyright by 20 years it brought back some works into p.d. The U.S. law handled it differently so that no works were so affected.)
But what I thought was misleading about his original post was his giving the orignal publication dates for the fairy tales. For non-English works, the date of first publication doesn’t matter unless you are using the original French or German or whatever. It’s the date of the English translation that counts when reprinting a fairy tale in English.
And works before 1923 are in the p.d., a big difference from pre-1900.
I should get the correct numbers in here someplace, too. Copyright was originally for 14 years plus a 14 year renewal, then went to 28 + 14, then to 28 + 28 before the Copyright Law of 1976 did away with renewals entirely.
Just to be completely even-handed, I’ll also nitpick myself. While the Copyright Law of 1998 explicitly references the Berne Convention, in practice the 20 year extension was tacked on to match what the European Union (and the UK) had already done, since the vast bulk of exports and imports of books are to those countries.