The pulley wheel as a perfect balance
A body hung by its ends, and a wheel centred on its axle acting as a balance
Two short propositions in mirror-script treat the wheel as a balance. The first states that a uniform body suspended by its opposite transverse ends distributes an equal share of its weight to each support; the second that a wheel whose axle-centre coincides with the centre of its circle acts in every case as a perfect balance, equal loads on opposite ends of its rim counterpoising one another. Two small diagrams at the left show a pulley with a wheel and a hanging weight 8, and a cylinder marked 8.
On this page
A uniform body hung by opposite ends loads its supports equally
A body whose parts between surface and centre are of equal material, weight and thickness, when suspended by its opposite transverse ends, gives an equal part and weight to each of its supports. It is the symmetric loading of a balanced beam.
A wheel centred on its axle is a perfect balance
A wheel whose pole-centre is the centre of its circle acts in all cases as a perfect balance; equal bodies hung from the opposite ends of its rim stand as equal counterweights one to the other.
Pulley and cylinder diagrams
At the left an upper sketch shows two small pulleys over a wheel from which a weight marked 8 hangs, and a lower sketch shows a cylinder or drum marked 8 with two suspension points. They illustrate the balance propositions.