20-century Germanic usage is not relevant, since this writer was a 17-th century Frenchman. At the time, the double 's' was prevalent all over Europe, including England.
Five lines lower (also two frames back, in the entry for 3 May 1700). one can see how the double 's' in the name Rousseau was written. The first (short) 's' in one case is fully formed and in the other is sharp, not rounded, at the bottom.
My actual question involves the assumption that "paisible" is the correct transliteration and I would still like an answer on that from someone with at least a near-native knowledge of French.