In the Memoires de l'Academie Royale de Prusse tome 1. from 1768, a summary of articles from the "Royal Society of Prussia" (the Königliche Akademie der Wissenschaften, Berlin Academy, or Prussian Academy of Sciences in Berlin) which picks up from 1745, after the original society merged with the Nouvelle Société Littéraire in 1744, we find the following on pp. 3-4:
Nous avons donc cru leur rendre le service le plus important, en detachant de ce precieux Recueil, & en leur presentant sous une forme peu volumineuse, & d'une acquisition facile, tout ce qui est le plus capable de les interesser dans les seize volumes in-4${}^\circ$. que l'Academie Royale de Prusse a publies, depuis son renouvellement sous Frederic II. surnomme le Grand a si juste titre.
(Sorry in advance for not using accents, it's so cumbersome with Windows)
We have therefore rendered [the physicians, chemists, anatomists, doctors, botanists, naturalists, etc of all Europe] the most important service, by extracting from this precious Collection, and presenting them under one less voluminous form, and easily acquired, all that is most capable of interesting them in the sixteen volumes in-4°. that the Royal Academy of Prussia published, since its renewal under Frederick II. surnommé the Great, and so rightly titled.
What does "in-4${}^\circ$." mean? I'm understanding it to mean something like "in the fourth decade" (1740s), but "in" isn't French, it's more likely a Latin expression.
