Yes, and “Gulliver” immediately adds, “... so that the squares of their periodical times are very near in the same proportion with the cubes of their distance from the centre of Mars, which evidently shows them to be governed by the same law of gravitation that influences the other heavenly bodies.”
What’s NOT said, is that the constant of proportionality in Kepler’s Law, which he cites, depends on the mass of the central body, namely Mars. Swift’s numbers show that he had a good estimate in hand, and I’ve always thought he must have had help with this. I believe that he did belong to some sort of intellectual circle of friends, but I’ve never seen any comment from literary sources about Swift’s calculations.
Gulliver’s travels was written in 1726 moons of Mars were not discovered until 1877 “Asaph Hall discovered both the Red Planet’s moons in 1877.” err?