What year ? What day ?
I could find some really early printed works, as early as
Anno Domini 50
De Alchimia Opuscvla Complvra vetervm Philisophorum ….. printed Anno Domini 50 in Francoforti ad Moenum (Frankfurt am Mainz) !
Francofoti ad Moenum, vndecimo Calendas aprilis, Anno 50
Source
I think it is safe to assume that these were indeed solar years, not lunar months.
Officially the book is printed “1550”, but Anno Domini 50 = Anno Domini 50, not Anno Domini 1550 … which would mean this count started “1501”.
Anno Domini 50, thus 50 years after the birth of Jesus?
Anno 78
Printed in the year 78, this german book called “Historia vnnd Beschreibung influentischer, elementischer vnd natürlicher Wirckungen, aller fremden vnnd heimischen Erggewechssen … by Leonhardt Thurneysser zum Thurn / doctor of the Churfürst Brandenburg. An early work about phytology.
Berlin, the 20 Day Februarij Anno 78
Source
Anno 77
A short report about a Comet, the 136th, first seen on the 19th day of October in the current year 77.
Ein kurtzer und einfeltiger Bericht / Leonhart Thurneyssers zum Thurns / Churf. Brandenburgischen bestalten Leibs Medici über den 136. Und in diesem lauffenden 77. Jar am 19 Tag Octobris erstlich erschienenen Cometen /
current year 77
Source
30. Februarij, Anno 1583
The same author Leonhardt Thurneysser zum Thurn wrote a book “Melisat kai hermeneia …” a kind of lexicon about languages and ethymology and wrote the prologue in this book in Berlin on 30. Februarij, Anno 1583
Berlin, the 30. Februarij, Anno 1583
Source
30 day of Februarij Anno 1583? Something smells fishy here.
For me, this is mockery of forgerers. Or ignorance at its finest, but I doubt that. It could not have been the case, that in “1583”, the private doctor of the Churfürst in Brandenburg would have released a book with such an erroneous date.
And merely a few months after the famous “Gregorian Calendar Reform”, allegedly in “1582”.
The "Thurneyssers"-Mystery on Google Books Ngram Viewer.
How is it possible, that Leonhard, Leonhart, Leonhardt Thurneyssers only appears after 1850???
Starting 1881
Starting 1850
What about his books officially printed in “1583”, “1587”, etc ?
Another spelling, same result: Leonhard Thurneissers
A lonesome peak a few decades before 1850
Why do these names NOT appear in Google Ngram viewer before 1850?
This is the name used by Google Books for the report about the comet .. oh my bad, it was written in Anno 77 and they just go back to “1500” ;-))
Name used by Google Books itself
I truly wonder if Leonhard Thurneyssers is an invented character from the creators of HIStory.