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Date: 1810-1830

Inventory Number: 2002-1-0023

Classification: Demonstration Apparatus

Subject:

Maker: American

User: John Farrar (1779 - 1853)

Cultural Region:

City of Use:

Dimensions:

67 × 67 × 5.8 cm (26 3/8 × 26 3/8 × 2 5/16 in.)

Description:

A mahogany hoop through which two wires are strung, one corresponding to a diameter, the other to a chord; one quarter of the rim of the object supports a brass rail. Each of the three elements, wires and rail, supports a solid brass sphere that can travel up and down the wire or rail.

Signedunsigned

FunctionThis apparatus shows two things. First, that the time of descent of a ball falling from the vertical diameter of the circle is equal to the time of descent of another ball falling from any of the circle's chords. (The diameter is, in fact, the longest chord of a circle.) Second, the ball falling from the chord and the ball following the curved perimeter of the circle will have the same speed at the base. Final speed only depends from the vertical height of the falling balls, not the path they follow.

For more explanation, with the mathematical equations, see the following website.

For more explanation, with the mathematical equations, see the following website.

Curatorial RemarksTag on instrument states: "From inventory of Professor Farrar assuming Hollis Chair dated June 25, 1807. Item 229 'A wooden circle with a wire diameter & chord, on which are two brass balls.'"

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