I'm well aware that two mutually exclusive statements cannot both be correct. Can we put that behind us? But if the contradictions are recognized, why are they repeated? Now my acceptance that the Earth rotates on its axis in 23h ... may not be directly observable, as stated in the previous paragraph, but there is evidence that it does rotate. Two items. One - as Neville J remarked in a recent post, the geosynchronous satellite is one -- it was doing 6000+ mph just before entering orbit, no braking was applied, where did the velocity go? 6000+ mph is not the measured velocity, since it assumes the earth rotates in the relative HC system. The orbital speed in the GS reference frame just before geo-stat orbit insertion is measured at about zero mph. The 6000 mph doesn’t go anywhere; it was never there to begin with. If we on the ground are moving at 67,000 mph in the HC system, why aren’t we in orbit like the satellites, which are moving much slower? In fact how can we be moving 11 times faster than the satellites? Remember: “I'm well aware that two mutually exclusive statements cannot both be correct.” …Two - if I experiment with a gymballed spinning gyroscope, I discover that the flywheel behaves in a quite predictable manner when its frame is rotated in different planes. If I leave the gyroscope spinning but its frame held -- apparently -- stationary, I observe that it behaves as though it were being manipulated just as before, except more slowly. I am entitled to believe that it is being manipulated by the -- apparently -- stationary object to which the frame is attached ie the Earth. And to head off any misunderstanding, I'm referring to the gyroscope's frame -- not frames of reference. [If I understand this description correctly??] the slow precession of the gyro gimbals is due to the torque of its own weight – the weight being caused by the downward flux of the firmament. It’s irrelevant to proving terrestrial rotation or not. If the gyro had a different shape or mass, the precession speed would be different – would we then conclude that the earth’s rotation speed had changed? Do you have any similar experiments which imply that the Earth is stationary, especially does not rotate? Paul D The Sagnac experiment and GPS daily operations. Robert