Poinsot was a contemporary of Léon Foucault, who invented the gyroscope and whose pendulum experiments provided incontrovertible evidence that the Earth rotates.
pˈɔɪnsɑːt wʌzɐ kəntˈɛmpɚɹˌɛɹi ʌv lˈeɪɑːn fˈaʊkɔlt, hˌuː ɪnvˈɛntᵻd ðə dʒˈaɪɹəskˌoʊp ænd hˌuːz pˈɛndʒuːləm ɛkspˈɛɹɪmənts pɹəvˈaɪdᵻd ɪŋkˌɑːntɹəvˈɜːɾᵻbəl ˈɛvɪdəns ðætðɪ ˈɜːθ ɹoʊtˈeɪts.