Observationes Cyclometricae by Adam Adamandy Kocha\'nski - Latin text   with annotated English translation
  Annotated parallel text in Latin and English of the classic paper of Adam Adamandy Kocha\'nski "Observationes Cyclometricae", published in Acta Eruditorum 4:394--398 (1685), in which he presented approximate geometric method of rectification of the circle, as well as a series of rational approximations of \pi. The included Latin text of Observationes closely follows the original text published in Acta Eruditorum. Punctuation, capitalization, and mathematical notation have been preserved. Several misprints which appeared in the original are also reproduced unchanged, but with a footnote indicating correction. Every effort has been made to preserve the layout of original tables. The translation is as faithful as possible, often literal, and it is mainly intended to be of help to those who wish to study the original Latin text. 
Henryk Fuk\'s
math.HO