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Pascal sent copies of his booklet to all his friends in Paris and to every town in France where he thought there were people who might be interested in reading it—presumably, to the local booksellers, for somewhere between fifteen and thirty copies went to Clermont-Ferrand alone; Mersenne sent copies to Sweden, Poland, Germany, Italy, and indeed all over the place.

What held them together was their common friendship with Mersenne, with whom they exchanged letters and at whose home they met when they were in Paris.

Publication was important within this group, but no more important than private and semi-public correspondence: Mersenne wrote letters to Italy, Poland, Sweden and Holland announcing Pascal’s Puy-de-Dôme experiment.

It is also significant that Mersenne’s friends collaborated without agreeing with each other.

The scientific network is another term for that sociological reality: Pascal announced his discoveries to Mersenne’s network, and persuaded them that his facts were right by getting them to repeat his experiments.