We find first of all that it requires us to assume that gravitational propagation is not instantaneous, but occurs with the speed of light. One might think that this is reason enough to reject the hypothesis, since Laplace demonstrated that this cannot be the case.3 In reality, however, the effect of this propagation is compensated in large part by a different cause, in such a way that no contradiction arises between the proposed law and astronomical observations.
Paragraph 13 introduction On the dynamics of the electron: Introduction
Einstein's Time Dilation is an Effect of Clock Synchronization
after having adjusted the watches by the optical procedure, we wished to verify the adjustment by the aid of these new signals, we should observe discrepancies which would render evident the common translation of the two stations. And are such signals inconceivable, if we admit with Laplace that universal gravitation is transmitted a million times more rapidly than light?
Laplace proved that the speed of gravity must be million times greater than speed of light,
I couldn't find his proof,
My question is how does he proved this to be true and how was it refuted?