Music is public domain, but my source document might not be

[Dulzian8]

Hi

Please could I get some copyright advise for the following situation:

Composer died in 1786.
The piece in question was published by the composer in a newspaper printed in 1733
Thus the music is most certainly in the public domain, no problem here.

My source is a doctoral thesis published at a German university in 1936.
It is a monograph about musicians in a geographical area and features a hand written appendix with 7 musical works (partially as excerpts only) which includes 2 short complete keyboard pieces that I am interested in typesetting. The source for his hand written appendix in my case was a library copy of the 1733 print. It is a very plain hand copy of the music with nothing more than the title, composer name and the music notation itself, devoid of any tempo markings, fingers or dynamics (but not short of a few obvious mistakes or omissions!)

I could so far not establish any biographical facts about the author of this dissertation but am still waiting for a few responses from people I contacted.
With the doctoral work published in 1936 it is fair to assume that the author is no longer alive, but for completeness of records and references materials and for the sake of establishing if the publication is still covered by the 70-years rule I am keen on finding some biographical facts about the author.

I could not confirm if the original 1733 print, which was used in the 1936 dissertation, still exists. The online search of the library (and across a network of libraries) which hosted this document does not return the any search results for these two pieces (some of the other manuscripts referred to in the dissertation are returned in the library searches). Neither do they seem to have results for for the newspaper in which this was published for the 1730s. The original manuscript could thus be:
- not indexed and scanned yet
- been moved to any other library in Europe during WW2
- been lost during or after WW2 (which would make our 1936 dissertation the only surviving source of the music)

I know of 3 CD records in the 15 or so years which recorded the two pieces in question and was able to get in contact with 2 of the 3 performers, both of whom confirmed they played from the 1936 hand written appendix.
A published edition of the complete organ works of the composer does not even mention these pieces, while discussing some of the composer's other music briefly.

Now I should think that a copy of an original 1733 print written out by hand does not meet the originality threshold to attract copyright on that part of publication.
At the same time, this is hardly an Urtext edition that would attract a 25 year protection only.
On the other hand I would expect that, being a doctoral thesis, it would have been expected to be prepared to a standard akin to that of an Urtext edition (as far as musical examples and appendices are concerned).

I am 98% certain that I am in the clear in terms of copyright, but do not want to step onto anybody's toes.
Thus, I would appreciate it if one of the copyright experts and reviewers could clarify the situation as to the above facts.

Thanks and kind regards
Marek