I am a figure skater, which helps me appreciate Newton's theory of mechanics.
Ha, but my life is a box of wormgears.
Only the flowing water is pure and sweet. Only the spinning top and the moving bicycle do not fall over. Rest is not found in irregular and purposeless motion, nor is it stagnation; all real and firm rest is to be sought in harmonious action.
I have discovered that a screw-shaped device such as this, if it is well made from starched linen, will rise in the air if turned quickly.
This excerpt is presented as reproduced by Copernicus in the preface to De Revolutionibus: "Some think that the earth remains at rest. But Philolaus the Pythagorean believes that, like the sun and moon, it revolves around the fire in an oblique circle. Heraclides of Pontus and Ecphantus the Pythagorean make the earth move, not in a progressive motion, but like a wheel in rotation from west to east around its own center."
We regard it as a certainty that the earth, enclosed between poles, is bounded by a spherical surface.
It's not magic! It's physics. The speed of the turn is what keeps you upright. It's like a spinning top.
The thing is, helicopters are different from planes. An airplane by it's nature wants to fly, and if not interfered with too strongly by unusual events or by a deliberately incompetent pilot, it will fly. A helicopter does not want to fly. It is maintained in the air by a variety of forces and controls working in opposition to each other, and if there is any disturbance in this delicate balance the helicopter stops flying; immediately and disastrously. There is no such thing as a gliding helicopter.
Yet if anyone believes that the earth rotates, surely he will hold that its motion is natural, not violent.
Arc, amplitude, and curvature sustain a similar relation to each other as time, motion, and velocity, or as volume, mass, and density.
The cause of the spinning wheel is too great and too good to have to rest on mere hero-worship.
The observations, so numerous and so important, of the pendulum as object are especially relevant to the length of its oscillations. Those that I propose to make known to the [Paris] Academy [of Sciences] are principally addressed to the direction of the plane of its oscillation, which, moving gradually from east to west, provides evidence to the senses of the diurnal movement of the terrestrial globe.
