This wikipedia article makes the claim:
"Bernoulli's correspondence with Euler (who also knew the above equation) shows that Bernoulli did not fully understand logarithms."
This is found under "History" . What does wikipedia mean here? Surely, Bernoulli understood what a logarithm was.
According to Bradley and Sandifer, eds., Leonhard Euler: Life, Work and Legacy, pages 259-260, Bernoulli, in correspondence with Euler, 1727-29, asserted $\log(-x)=\log x$. There's more to it than that, the book goes into some detail.