https://mathshistory.st-andrews.ac.uk/Biographies/Boulliau/
Ismael Boulliau (1605 - 1694) - Biography - MacTutor History of Mathematics
Ismael Boulliau or Bullialdus was a French clergyman and amateur mathematician who proposed an inverse square law for gravitation before Newton.
history ofismaelbiographymactutormathematics
https://adcs.home.xs4all.nl/Huygens/04/190-boulliau.html
Chr. Huygens, Briefwisseling met Boulliau, 1662
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