Pierre des Noyers (1608–1693), a disciple of Gilles Personne de Roberval, is the most important correspondent of Johannes Hevelius. Their correspondence consists of 257 letters, in a corpus of 2700 letters, i.e. about 10% of the total. Pierre des Noyers came to Poland with Queen Louise-Marie de Gonzague. During his Polish travels he spent some time in Gdańsk (December 1646) and met the astronomer who was a prominent member of the city elite, as one of the most important brewers. During this period, Hevelius was completing his Selenographia (1647) and Pierre des Noyers was very helpful in expanding a European network that already included Marin Mersenne and Pierre Gassendi. The relations between the two scholars were very intense. After the death of the Queen (1667), des Noyers stayed in his friend’s house. The last letter is dated October 1686. Hevelius died in January 1687. Pierre des Noyers remained in Poland where he died in 1693. At this point I would like to present some conclusions based on my analysis of this correspondence, thereby introducing the third volume of the series Correspondance de Johannes Hevelius to be published in 2019.