hˈɪɹ hiː kəŋklˈuːdᵻd ðætðə dˈɪfɹəns bᵻtwˌiːn ðə dˈɛnsᵻɾi ʌvðɪ ˈɜːθz sˈɜːfɪs ɹˈɑːks ænd ðə mˈiːn dˈɛnsᵻɾi ʌvðɪ ˈɜːθ mˈɛnt ðætðɪ ˈɜːθ mˈʌstɐv ɐ hˈɛvi ˈaɪɚn kˈoːɹ.
Here he concluded that the difference between the density of the Earth's surface rocks and the mean density of the Earth meant that the Earth must have a heavy iron core.