As shown in the documentary Behind The Curve, they used the gyroscope, ran their experiment, and conclusively showed, beyond a shadow of a doubt, that the Earth rotates on its axis and drifts 15 degrees every hour. Knodel and Campanella spent $20,000 on a high-end machine that proved exactly what every kindergartner in America already knows: The Earth is round. And they didn't even get a juice box as a reward.
You'll not be shocked to learn that Knodel did not accept his own findings. He continually concocted various ways to "fix" his own experiment, only to keep finding that pesky 15-degree shift every hour. It's almost as if the Earth isn't shaped like a Frisbee covered in a punch bowl at all.