Since tides caused by the Moon’s: The Earth’s angular velocity in its spin around its axis is higher than the angular velocity of the Moon in its orbit. Consequently, the tidal forces tend to spin the Earth down and to increase the Earth-Moon distance.

“It is impossible, with the imperfect data”: Kelvin 1868.

George was a physicist: While in Trinity College in Cambridge, George Darwin (1845–1912) was Second Wrangler and Second Smith’s Prizeman.

even a solidified Earth was not: Darwin repeated the result of his 1878 letter considering the rigidity of the Earth in his presidential address to the British Association in 1886 (G. H. Darwin 1886), concluding that he saw no right to be “so confident of the internal structure of the earth as to be able to allege that the earth would not through its whole mass adjust itself almost completely to the equilibrium figure.”

Charles Darwin was delighted: G. H. Darwin in Stratton and Jackson 1907–16, vol. 3, p. 5.