Dr. Samuel Birley Rowbotham discusses the Foucault Pendulum and its movements in Chapter 14, Section 8 of Earth Not a Globe. Rowbotham provides additional insight in Chapter 14, Section 21.
Summarily, the line of the pendula must be 25 meters in length to get the minimum effect, and so by necessity, Leon Focault's original experiments between latitudes were conducted outside hung from a tree exposed to the elements. Dr. Rowbotham finds that the variations of the pendula are caused entirely by the contraction and expansion of its line due to temperature variations upon the earth's surface in relation to the nearness of the Sun. These variations match up perfectly with the official published results of Focault's experiments.
The Wrong Way
The Focault Pendulum is often seen to move in the wrong direction. See the following quotes:
“Astronomers have made experiments with pendulums which have been suspended from the interior of high buildings, and have exulted over the idea of being able to prove the rotation of the Earth on its ‘axis,’ by the varying direction taken by the pendulum over a prepared table underneath – asserting that the table moved round under the pendulum, instead of the pendulum shifting and oscillating in different directions over the table! But, since it has been found that, as often as not, the pendulum went round the wrong way for the ‘rotation’ theory, chagrin has taken the place of exultation, and we have a proof of the failure of astronomers in their efforts to substantiate their theory.”
—100 Proofs the Earth is Not a Globe, William Carpenter
“We believe, with all due deference to the pendulum, and its proprietor, that it proves nothing but the craftiness of the inventor; and we can only describe the show and showman as deceptions. A thing so childish as this ‘pendulum proof’ that it can only be described as one of the most simple and ridiculous attempts to gull the public that has ever been conceived. It has been said that the pendulum experiment proves the rotation of the earth, but this is quite impossible, for one pendulum turns one way; and sometimes, another pendulum turns in the opposite direction. Now we ask does the earth rotate in opposite directions at different places at one and the same time? We should like to know. Perhaps the experimenters will kindly enlighten us on this point … If the earth had the terrible motions attributed to it, there would be some sensible effects of such motions. But we neither feel the motion, see it, nor hear it. And how people can stand watching the pendulum vibrate, and think that they are seeing a proof of the motions of the earth, almost passes comprehension. They are, however, brought up to believe it, and it is thought to be ‘scientific’ to believe what the astronomers teach.”
—The Romance of Science (8-10), Lady Blount
Mach's Principle explains that if the earth was still and the all the stars went around the Earth then the gravitational pull of the stars would pull the pendulum. As Mach said "The universe is not twice given, with an earth at rest and an earth in motion; but only once, with its relative motions alone determinable. It is accordingly, not permitted us to say how things would be if the earth did not rotate."