Natural Philosophy 181it required evidence of productive engagement with natural philosophy
(or some other science) for admission. Another example is the Società
Italiana delle scienze, founded in 1782 to strengthen ties among the natu-
ral philosophers of the peninsula. Despite its mission of inclusiveness, the
society applied the tightest tests of the time, to the approval of those who
passed it. The polymath peripatetic Jesuit physico- mathematician Roger
Boscovich wrote the society’s founder: “I’m glad that your Società Italiana
is progressing and I entirely agree that it will be very good to restrict the
number [of its members] so as not to make it a Noah’s arc.” Similarly,
the Hollandsche Maatschappij der Wetenschappen, which had begun in
1758 with a membership representative of all the literate animals in na-
ture, had restricted itself by the end of the century to “professionals who
are professors, or have acquired their reputations by [their] work.”^23 The
rise in the proportion of professionals and professors in the academies
coincided with an explicit acknowledgment of the arrival of exact natural
philosophy. In 1785 the Paris Academy added a new class of “experimen-
tal physics” to its group of mathematical sciences. Likewise, in 1807 the
Hollandsche Maatschappij established a new division for “experimental
and mathematical sciences.”
The Hollandsche Maatschappij’s specifi cation of ideal academic types
included two novelties: professionals and professors. By professionals they
appear to have meant natural philosophers like Martinus van Marum,
a physician by training, director and curator of instruments for the
Maatschappij and also for Tylers Tweede Genootschap, a small general-
purpose learned academy with a substantial museum and collection of
apparatus. Van Marum demonstrated, lectured, experimented, and mea-
sured (though not often) in return for several salaries. Professionals also
included men like Van Marum’s associate Adriaan Paets van Troostwijk, a
merchant by trade and a serious chemist by avocation. His professional-
ism in natural philosophy lay in the new fi eld of pneumatics, especially
the ventilation of mines, prisons, and factories, and the action of electric-
ity on the gas types, about which he manufactured much exact mislead-
ing data.^24 As for professors, their appearance among desirable academics
indicated an important development, even a revolution, in the Republic
of Letters. The great academic movement of the eighteenth century fi lled
a niche not occupied by the universities. Professors taught; academicians
worked to advance knowledge and to apply it usefully. As the Encyclopédie
laid it down, “An academy is by no means intended to teach or profess
any art, no matter what it is, but to perfect it.” That implied a risk. “An
academician must invent and improve,” so said one of the founders of the